Midterm 1 - Lectures Flashcards

Question

What did theoretical and experimental geneticists focus in the modern synthesis era?

Answer 1

Changes within species rather than the origin of new ones.

Answer 2

Focus on using DNA technology to characterize variation within species.

Answer 3

Ethological isolation

Answer 4

Differences in sexual preferences between species that prevent them from mating.

Answer 5

Began in the early 80s

Answer 6

New molecular tools allowed novel and more powerful approaches to old questions.

Answer 7

That ecological approaches to speciation have been neglected, which in return helped in long-term field studies.

Answer 8

Was the first to emphasize the link between sexual selection and speciation. Populations under divergent sexual selection could become behaviourally isolated (no longer recognize the other).

Answer 9

Changes in mating signals and female preferences that leads to another specie emerging, and thus reproductive isolation.

Answer 10

1. Continuation of genetic approaches 2. Mathematical theory 3. Emphasis on ecology 4. Molecular analysis 5. Comparative studies (last 4 are novel)

Answer 11

Those that don't allow organisms to interbreed with one another: - pre-zygotic: prevent mating from occurring like different mating habitats, rituals, or genitals - post-zygotic: reduce the viability (in viability) of the zygote or the fitness of the offspring (sterility)

Answer 12

Went against the idea that all species were created from God's period as he believed that species can constantly change and evolve.

Answer 13

Someone who observed organisms in the wild.

Answer 14

We act as they are real: - naturalists label specimens - systematists reconstruct relationships among species - population geneticists measure DNA variation within species - ecologists calculate species diversity and document extinct species

Answer 15

They claim species are subjective divisions nature for human convenience. This is because mating systems that plants have make it more difficult to consider a species' boundaries

Answer 16

He didn't think they were real and he believed that the classification of organisms was a matter of convenience and not an objective way of summarising diversity in nature.

Answer 17

That evolutionists who doubted the validity of species acted as they were real when doing their own research such as using the Linnaean names.

Answer 18

1. Arguments from common sense 2. Agreement between 'indigenous' and 'scientific' species classifications (compare those long time ago that aren't trained in species) 3. Statistical identification of clusters (measure traits of certain animals and see whether the ones you would normally group together as a species, cluster together)

Answer 19

They are real because everyone recognises they are real. Dobzansky quoted that formation of discrete groups is universal that it must be regarded as a fundamental characteristic of organic diversity.

Answer 20

Clusters are often discrete even to causal observers - there is no continuum between eagles and crows or hummingbirds and parrots (so distinct)

Answer 21

The usefulness of field guides is proportional to the discreteness of taxa (can identify the differences between different species).

Answer 22

Humans have the tendency to divide a continuous array of organisms into discrete units. ex. dividing the continuous wavelengths of a rainbow (shorter; violet to longer; red) into discrete colours

Answer 23

Indigenous people from Arfak Mountains of New Guinea had 136 names for 137 recognized Linnaean species of birds.

Answer 24

If multiple different observers can observe the same phenomenon, can prove the validity of it.

Answer 25

Found 80% correspondence with Fore people of New Guinea and Linnaean birds. They were even taken to lower elevations and asked to name birds that they had never encountered and 90% of 103 Linnaean species were recognized as distinct. Therefore, the correspondence from two dissimilar classification systems show the objective reality of the species.

Answer 26

The Tzeltal people of southern Mexico had 471 indigenous names for plants in their area which were 66% identical to the Linnaean species.

Answer 27

Geographic variation, so the same species could look quite different in different habitats (giving less overlap). They need to look at the same ones in the same habitat.

Answer 28

At least 70% correspondence between Indigenous and Linnaean species in various studies. This strongly supports the view that people of different scientific backgrounds recognize similar units of natural diversity.

Answer 29

The appearance classification connected to the morphology (measuring plumage, recording songs) line up perfectly to DNA recordings.

Answer 30

In many interactions they can identify the correct species: - male robins court the correct female robin - pollinators recognize specific species of plants - host-specific herbivores and parasites recognize specific species

Answer 31

Measure a bunch of traits from one species and compare those of another species, do they cluster together based on relatedness.

Answer 32

Morphological, behavioural, reproductive, and molecular traits.

Answer 33

Using discriminant analysis of morphology in sunfish and shiners showed that sympatric species were well differentiated (clustered together) and the hybrids were intermediates between clusters.

Answer 34

Strong similarity between species classification by morphology and DNA.

Answer 35

Mayr studied vascularized plants in Concord Woods Massachusetts and 838 species, 80%, were easily distinguished by morphology (9% of named species did not correspond well).

Answer 36

No necessarily: - usually rare and sterile - frequency of hybridizing plants is less than 6%

Answer 37

Due to variable mating systems.

Answer 38

Sexually reproducing ones

Answer 39

Most biologist believe species are real but the higher taxa are not because these groups are less distinct making it more difficult for a normal person to distinguish between the two (are a hummingbird and parrot related).

Answer 40

It breaks down

Answer 41

The subdivision of trees into vines, grasses, and broad-leafed herbs highlight evolutionary convergence among distantly related taxa (not close relationships). Some that look similar and not genetically related, so higher order classification is more tricky.

Answer 42

Grouped together orders by similarity not functional or economic considerations. Their five group orders are: - hefa (eels, cassowaries, large marsupials, and rodents) - nema (bats, all birds except cassowaries) - hoiafa (lizards, snakes, fish, molluscs, worms, and centipedes) - hera (frogs other than those of three genera)

Answer 43

1. Vegetative reproduction 2. Self-fertilization 3. Production of seeds or eggs without sexual reproduction (apomixis or agamospermy; seeds produced from unfertilized ovules).

Answer 44

It is quite rare and leads to genetic clones.

Answer 45

Trade-offs between forms of reproduction where core diploid species undergo sexual reproduction and these species hybridize to form polyploids. Most often then reproduce agamospermy but sometimes can undergo sexual reproduction. ex. dandelion diploids can form hybrids can form octploids (some cannot reproduce with each other)

Answer 46

2000 microspecies

Answer 47

No, they are not all unqiue and isolated from other species. This is because after his 132 classifications of dandelion in British Isles, botanists could only identity 40% of them.

Answer 48

Three botanists had three different answers (24, 205, and 494 species). This meant these classifications weren't universally recognizable .

Answer 49

To perform cluster analysis on many sympatric individuals.

Answer 50

Sepp and Paal studied the Lady's mantle, which had more than 1000 microspecies. Examined 43 morphological traits across 23 species in Estonia, and the traits all clustered together. Three were distinct (be cautious of these claims because not much lacking statistical support).

Answer 51

A group of organisms that are genetically distinct (not greatly) but morphologically similar to others. Can usually arise through asexual reproduction.

Answer 52

Speciation, which is the act of one species becoming two.

Answer 53

Through asexual reproduction, transduction, transformation, conjugation, and horizontal uptake (naked DNA in their environment). ex. 18% of genes in E. coli acquired this way

Answer 54

They are distinct. ex. Barrett and Sneath studied 315 strains of the endoparasitic bacterial genus Neisseria. They analyzed 155 phenotypic traits and found 31 distinct phenotype clusters. Clusters included strains with diverse hosts, and the most difficult to distinguish were the sympatric ones (human nasopharnyx).

Answer 55

Based on Mayr's Biological Species Concept and those based on morphological differences (Typological Species Concepts).

Answer 56

More than 25.

Answer 57

Because not one concept is free from ambiguity when it's applied to nature (rare hybrids, geographic variation, etc.); species evolve from other species, and during this process there will be some unclear cases; and no single species concept can encompass sexual taxa, asexual taxa, and those with mixed models of reproduction.

Answer 58

1. Help us classify species in a systemic manner 2. Correspond to discrete entities we see in nature 3. Help us understand how discrete arise in nature 4. Represent evolutionary history of organisms 5. Apply to the largest possible number of organisms

Answer 59

Why do sympatric, sexually reproducing organisms fall into discrete clusters?

Answer 60

The observation of discrete sexually reproducing groups in sympatry immediately suggests a species concept based on interbreeding and its absence. Recognized by Dobzhansky.

Answer 61

Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.

Answer 62

Biological features of organisms that impede the exchange of genes with members of other populations.

Answer 63

1. Behavioural isolation 2. Ecological isolation (habitat; temporal; and pollinator) 3. Mechanical isolation 4. Mating system isolation

Answer 64

1. Copulatory behavioural isolation 2. Gametic isolation (noncompetitive or competitive)

Answer 65

1. Extrinsic (ecological inviability and behavioural sterility) 2. Intrinsic - hybrid inviability - hybrid sterility (physiological and behavioural)

Answer 66

Limited hybridization may be fine as species status can be a sliding scale: - as gene flow decreases, they become more species-like - when reproductive isolation is complete, good species

Answer 67

- several instances of one species replacing another close relative in nature (occupy same niche and the role), maintaining species status despite ecological similarity - ecologically differentiated taxa lacking reproductive isolation can fuse in sympatry/hybridize - ecological differentiation is neither necessary nor sufficient for speciation

Answer 68

Most isolating barriers are genetic but the geographic barriers that play a role in allopatric speciation are not isolating barriers (initiate speciation process but do not continue it fully). This is because they do not prevent gene flow between sympatric species and do not involve biological differences between taxa (can lead to them involving).

Answer 69

Cannot perform all possible hybridizations of all species, but can infer reproductive isolation from morphological (might not recoginze and mate with one another), chromosomal, or molecular traits.

Answer 70

BSC is concerned with isolating barriers operating at present, but these forms can disappear with a change in environment. ex. human disturbance has resulted in the formation of hybrid swarms in Iris

Answer 71

Intrinsic postzygotic isolation is efficient at preventing fusion. Developmental pathways can become less compatible in hybrids (sterility and inviability). As time passes, the probability of reversing all incompatibilities approaches zero as more isolating barriers become apparent.

Answer 72

It helps solve the species problem: 1. Explains the existence of discontinuities among sexually reproducing organisms living in one area 2. Phylogenetic species can be recognized as discrete tips in phylogenies but do not tell us WHY the tips are discrete 3. Suggests a research program to reduce "the origin of species" to "the evolution of isolating barriers"

Answer 73

1. Biological species are best diagnosed in sympatry but many taxa are geographically isolated and morphologically differentiated populations (ex. North American elk and European red deer are both Cervus elaphus but differ in size and colour). Testing these predictions would be very difficult 2. In African rift lakes, dozens of cichlids are classified as species based on colour but we do not know if these differences would prevent hybridization in sympatry

Answer 74

No, as some can exchange migrants and migrants have the ability to interbreed to establish a species status.

Answer 75

Only a problem if one adheres to a strict BSC where no gene flow is permitted.

Answer 76

1. Much hybridization caused by human disturbance 2. Hybridization may be transient phase during sympatric speciation and reinforcement 3. Some apparent hybrids may be geographic variants or non-genetic variants produced by local conditions

Answer 77

Is a rampantly hybridized or well differentiated species. Botanists have paid great attention to them.

Answer 78

BSC cannot deal with species where sexual reproduction is rare or absent.

Answer 79

Cannot but is the groups form distinct clusters in sympatry, should use species concepts that address the origin and maintenance of these clusters.

Answer 80

1. This will be a problem under any species concept as it's somewhat arbitrary but necessary for scientific communication.

Answer 81

Look at intermediary areas. Two different species in different habitats and no intermediate between them, then physically isolated and different species.

Answer 82

More predictable when in a single location.

Answer 83

Based on discontinuities between phenotypes. Cannot do colours or vocalizing isolating barriers.

Answer 84

BSC is severely criticized by systematists (doesn't always apply). Populations of a single species can be less closely related than populations of different species. Evolutionary histories of different genes can differ from history of taxa as a whole.

Answer 85

Group of organisms that share a common ancestor but not all of its descendants

Answer 86

Interbreeding.

Answer 87

Using mtDNA. But it can be misleading too.

Answer 88

Species exist because they are discrete stable states formed by the self-organizing properties of biological matter.

Answer 89

It lacks mechanisms to explain such states, does not explain origin of new stable states, and geographic variation in traits casts doubts on the stability of species.

Answer 90

Because they fill discrete ecological niches, thus relying on trade-offs.

Answer 91

There are no intermediary levels, so hybrids are viewed as unfit and only the extreme phenotypes take suit.

Answer 92

No because it relies on isolation from extrinsic barriers.

Answer 93

Reproductive isolation is an inevitable result of evolutionary divergence.

Answer 94

Only those species that are sexually reproducing.

Answer 95

Ecological niches as adaptations can lead to reproductive isolation.

Answer 96

Anisogamy, which are different sizes of male and female gametes, leading to the possibility of sexual selection. A diverging one can lead to behavioural or gametic isolation.

Answer 97

Through the occupation of new ecological niches through periodic selection or macromutations.

Answer 98

Ecological diversification

Answer 99

Ecology and reproductive isolation.

Answer 100

Ecological explanation

Answer 101

That there is genetic and phenotypic cohesion = within a species, individuals share a significant degree of genetic similarity and exhibit similar observable traits (phenotypes), which helps to maintain a recognizable group identity. This is through gene flow.

Answer 102

That there is evolutionary cohesion.

Answer 103

Evolutionary history = how organisms are related to each other, including which species they evolved from and which species they are most closely related to.

Answer 104

The process by which species adapt to different habitats, which can lead to the emergence of new species.

Answer 105

Mannequin birds, ecological similar by diet and morphology (similar niches in habitats); however, they occupy different geographic areas (not in the same habitat) leading to different species.

Answer 106

That they can only be defined relative to other species.

Answer 107

Evolution within lineages

Answer 108

Every species concept requires comparing different groups of individuals: - morphological distinctness - ecological distinctness - phylogenetic distinctness

Answer 109

One gene that affects multiple traits

Answer 110

Characters that evolve within one group have side-effect producing isolating barriers with other taxa

Answer 111

Adaptation to a new habitat can automatically lead to spatial isolation.

Answer 112

Selection for adaptive differences can lead to intrinsic hybrid inviability or sterility.

Answer 113

Effect of one gene depends on genetic background

Answer 114

Genes evolving in one group produce reproductive isolation by interacting with genes evolving in other groups.

Answer 115

Intrinsic hybrid inviability or sterility OR behavioural isolation due to changes in males in one lineage and changes in females in another.

Answer 116

Due to complex interactions between genomes of two taxa.

Answer 117

Emergent properties.

Answer 118

1. Which reproductive barriers are involved in the initial reduction in gene flow? 2. Which evolutionary forces produced these barriers?

Answer 119

No, they continue to accumulate.

Answer 120

Yes they can distort historical importance, especially in sympatric species. ex. monkeyflowers Mimulus lewisii and M. cardinalis overlap in the Sierra Nevada mountains where they have different pollinators in sympatry providing different phenotypic differences

Answer 121

Sequentially over the life of the organism, beginning with habitat and temporal isolation in adults and ends with hybrid sterility and inviability.

Answer 122

Reduces the gene flow that has escaped previous barriers.

Answer 123

The earlier ones even though the later ones may be stronger.

Answer 124

Hybrid sterility evolves faster than hybrid inviability.

Answer 125

Both barriers will become complete and hybrids will be inviable.

Answer 126

Hybrid inviability as no hybrids will appear.

Answer 127

Absolute strength

Answer 128

What proportion of gene flow the barrier blocks?

Answer 129

The current relative importance and/or historical importance.

Answer 130

The isolating barrier played a major role in speciation.

Answer 131

Its usefulness for genetic studies.

Answer 132

Relative strength

Answer 133

The proportion of gene flow blocked relative to other barriers.

Answer 134

Must measure all possible forms of isolation and the order in which they act.

Answer 135

The relative importance of barriers that prevent species from fusing.

Answer 136

Cannot tell us which barriers caused speciation.

Answer 137

Prezygotic isolation because since barriers act sequentially, it is probably the strongest one to impede gene flow/

Answer 138

Ecological divergence and mate choice assumed to be more important for speciation in Heliconius butterflies, but some species also show evidence of postzygotic isolation.

Answer 139

There are no hybrids and we know nothing about the strength of postzygotic isolation. ex. two allopatric bird populations diverge in male colour and female preference --> hybrids of intermediate colour cannot find mates --> leads to reinforcement that completes isolation --> with no more hybrids, would be impossible to know that behavioural sterility was critical in speciation

Answer 140

Via hybrid sterility it is important in restricting gene flow between ancestral species and newly formed polyploid or diploid hybrid descendants.

Answer 141

Ecological prezygotic barriers

Answer 142

May involve the same differences in ecology or sexual behaviour that cause prezygotic isolation, such as disruptive selection or sexual selection making hybrids unfit.

Answer 143

Habitat isolation --> temporal isolation --> behavioural isolation --> mechanical isolation --> gametic isolation

Answer 144

Reduced hybrid viability --> reduce hybrid fertility --> hybrid breakdown

Answer 145

The persistence of distinct taxa in the face of hybridization suggest that hybrids are at a disadvantage. ex. 19% of Lepidopteran species hybridize and the hybrids of mimetic Heliconius butterflies are less attractive to mates and more vulnerable to predators due to being intermediate in colour and behaviour

Answer 146

For reinforcement to increase isolation, must be some postzygotic isolation that makes hybridization disadvantageous.

Answer 147

Intrinsic postzygotic isolation is more likely to be permanent. This is because it's difficult to undo hybrid sterility and inviability based on genetic incompatibilities. Selection would have to act on the same exact genes, restoring original alleles.

Answer 148

Those based on phenotypic divergence can easily be reversed as they involve genes different from the original.

Answer 149

In separate studies of Drosophila and Helianthus sunflowers, parts of the genome that have not introgressed (mixed) in hybrid zones are those that cause intrinsic hybrid sterility.

Answer 150

The transfer of genetic information from one species to another as a result of hybridization between them and repeated backcrossing (parent and hybrid).

Answer 151

These genes are associated with chromosome rearrangements. Association would not exists if hybrid sterility evolved after speciation.

Answer 152

Reduced movement through hybrid zones which provides evidence that postzygotic isolation operated in the past and continues to operate prevent introgression.

Answer 153

Asymmetry between how pre and postzygotic isolation behave beyond F1.

Answer 154

In F2 generation and backcrosses.

Answer 155

Because many hybrids behave like pure species.

Answer 156

They increase the sterility and inviability of these hybrids.

Answer 157

Could study geographic populations of a single species to determine which barriers exist in the initial or early species.

Answer 158

Most populations never become species and even if a single barriers is first to arrive, it's impossible to determine its later influence.

Answer 159

Comparative analysis of multiple taxa at different stages of evolution is more promising.

Answer 160

1. Sympatric species with few isolating barriers 2. Hybridization following ecological disturbance 3. Isolating barriers associated with chromosome rearrangements 4. Comparative studies of evolution of reproductive isolation 5. Comparative studies of traits promoting speciation

Answer 161

Postzygotic isolation via chromosomally-based hybrid sterility.

Answer 162

Only if there is sufficient ecological differences to co-exist with diploid ancestors.

Answer 163

Preference for and ability to survive on different hosts.

Answer 164

Gametic isolation and can co-exist because of it.

Answer 165

If an ecological disturbance causes previously isolated species to fuse or form hybrid swarms. ex. in lake victoria, there is a positive correlation between number of cichlid species and water clarity (male colour only visible in clear water).

Answer 166

If the genes causing reproductive isolation reside within chromosome regions that are rearranged, association will persist when species come into secondary contact.

Answer 167

Recombination between genes within rearrangements.

Answer 168

The elimination of genes by natural selection against hybrids leading to delayed fusion of species and allowing other barriers to accumulate.

Answer 169

The strength of barriers and the time of divergence between taxa.

Answer 170

Work by Wilson showed that mammals could produce viable hybrids after 2-3 millions years of divergence, frogs after 21 million years, and birds after 22 million years. NOTE: 22 million years would be equivalent of humans and gibbons producing hybrids.

Answer 171

That prezygotic isolation appears to evolve faster (develops at 0.75 whereas for the postzygotic one is takes over 1.0). Disparity is due to biogeography and sympatric taxa diverged faster (more pressure).

Answer 172

There are only a few others; missing barriers in every group; and most measure the barriers in ONLY Drosophilia, darters, and plants.

Answer 173

Intrinsic hybrid sterility and inviability as there is no recently diverged taxa with sterile or inviable hybrids.

Answer 174

Hybrid sterility evolves faster than hybrid inviability.

Answer 175

At different rates in different groups.

Answer 176

Animal pollination of plants and those associated with sexual selection in birds and insects.

Answer 177

Phenotypic differences that stop mating OR they cannot recoginze each other. ex. plummage colour on birds

Answer 178

Mating at different times of the day.

Answer 179

Plant species have different pollinators that visit them. ex. hummingbird or bee

Answer 180

Lock and key mechanism - reproductive parts do not fit.

Answer 181

Plant species have different reproductive strategies. ex. agametic or ploidy levels

Answer 182

Heterospecific and conspecific not interacting at the same time.

Answer 183

Hybrid intermediate in morphology so ill-suited to different habitats, might not survive.

Answer 184

Survived to age of reproduction, but nobody wants to mate with it.

Answer 185

Cannot survive to maturity due to a physiological defect.

Answer 186

Do survive to reproduce, but cannot properly reproduce.

Answer 187

200 genes involved in hybrid inviability with each one causes nearly complete hybrid inviability itself. A lot of genes important in reproductive isolation, but only need a few. This makes it difficult to isolate which one caused it first, especially as they evolve and separate.

Answer 188

Habitat isolation accounts for 59% of reproductive isolation and pollinator isolation accounts for 98%. Hybrid inviability results in 12% of reduction in gene flow. With all these different barriers, unsure which one evolved first. Any combination of three barriers reduces gene flow to nearly zero (don't need them all, so it doesn't mean they are all important in the speciation process).

Answer 189

Natural selection acting on species to provide reproductive isolation.

Answer 190

Closely related species that lives in the same lake but segregated by body size and feeding regimes. It would change if the lake becomes uniform, barriers ceast to be important. Postzygotic barriers more important as they involve deep rooted genetic changes.

Answer 191

Plotted pre/post - zygotic isolation with genetic distance (how long they had been isolated).

Answer 192

Birds very distantly related could still mate with each other (0 postzygotic isolation). This just means that the strength of barriers can differ in groups.

Answer 193

Speciation with complete geographic isolation.

Answer 194

With limited genetic exchange.

Answer 195

With free gene flow.

Answer 196

Allopatric

Answer 197

1. Vicariant speciation 2. Peripatric speciation

Answer 198

Geographic range of a species splits into two or more large populations.

Answer 199

Isolated habitat colonized by a few individuals or a small population becomes geographically isolated.

Answer 200

Due to climate or geology: - formation of land bridge - glaciation - elevation of mountains - continental drift - climatic change - extinction of intermediate populations

Answer 201

Yes, because gene flow is uninterrupted.

Answer 202

They are adapting to new habitats where they can develop new mutations through genetic drift. All this coupled with no gene flow allows isolating barriers to develop.

Answer 203

Mathematical models through drift alone, drift and selection, and sexual selection.

Answer 204

Evidence as few as 18 generations for flies showed prezygotic isolation were a byproduct for selection. Postzygotic isolation were low probably need longer generations.

Answer 205

Geographic concordance of species borders with geographic or climatic barriers. ex. Isthmus of Panama

Answer 206

North America and South America were separated before and this allowed species to easily move from one side to another.

Answer 207

13 pairs of sister species in Pacific and Atlantic. One species in the past but when the land barrier came in, they separated over time. Only 1% of matings could yield fertile clutches in lab.

Answer 208

Once connected continents, but when separated a long time ago, the species diverged more recently based on climate change. Cooler and drier climates replaced the forest habitat with grassland, that's why more restricted to eastern areas. Each of genera have one sister species in north America and one in Asia.

Answer 209

Allopatry of young sister species (each other's closest relative). Sister species within a group always occur in allopatry even if no geographic barrier.

Answer 210

Sister species are always allopatric whereas older ones can overlap.

Answer 211

Geographic coincidence of species borders or hybrid zones among different taxa. Can infer speciation in allopatry where a present distribution reflects secondary contact after disapperance.

Answer 212

Must know that a barrier used to exist. Must not be an ecotone barrier where species ranges meet (transition between two biomes).

Answer 213

In S. America, Pleistocene advance of glaciers reduced precipitation and temperature and produced refugia, small patches of forest. This produced multiple speciation events. Look at Charis butterflies; sister species viewed populations are completely separated (allopatric) or parapatric. Seen seven areas of endemism identical to those derived from phylogenies of reptiles, birds, rodents, primates, etc.

Answer 214

6 major zones where they contain many hybridizing plants, insects, mammals, etc. These zones correspond to the sites of former geographic barriers (secondary contact between allopatric ones). ex. red shafted flickers found on west and east coasts OR bullock's oriole and baltimore oriole's

Answer 215

Absence of sister species in areas where geographic isolation was unlikely. Need barriers to produce speciation. ex. Coyne and Price surveyed 51 remote oceanic islands never connected to mainland; found no sister species of bird; only found when species could move to different island (allopatric speciation)

Answer 216

Concordance between present or past geographic barriers and genetic discontinuities between species (where there was once a barrier, can show genetic differences) - abrupt changes in allele frequencies within species - changes occur in similar locations across species

Answer 217

Patterns show that geographic isolation promotes genetic diveregence, not speciation. This is because you are still looking at individuals part of the same species.

Answer 218

Glaciation in the past had no pennisula in Flordia, so animals could move freely. Introduction of Florida has created a barrier (bigger during past glaciations), more water after retreated, created a bit more movement. Allele frequencies change from one side of pennisula to another: horseshoe crab, ribbed mussell, etc.

Answer 219

Increase in reproductive isolation with geographic distance between populations.

Answer 220

Remote populations may exchange genes only rarely allowing for fairly independent evolution.

Answer 221

If ecology changes geographically, it could be due to local adaptation rather than geographic isolation itself. Therefore, it's not fully due to allopatric speciation

Answer 222

1. Strepthanthus glandulosus plants 2. Desmognathus ochrophaeus salamander 3. Tigriopus californicus copepod 4. Timema cristinae stick insects - their genetic distance increases as you move farther distances between their species

Answer 223

Encircles a geographic barrier like a mountain or plateau where ancestral populations gradually expand their range around the barrier. Exchange gene flow freely expect where they meet at the other end of the barrier (genetically/reproductively isolated for so long).

Answer 224

The attentuation (reduction) of gene flow with distance NOT allopatric speciation.

Answer 225

Clinal isolation can be caused by environmental differences that increase with distance between populations. Cannot make the same argument with ring species since the most reproductively isolated populations occur in the same habitat. Not habitat driving it, genes are.

Answer 226

1. Ring was founded by one population rather than two or more genetically distinct populations 2. At least one of the terminal populations must represent the most recent range expansion 3. There must be no present or past geographic barriers around the ring to interrupt gene flow 4. Gene flow is extensive between adjacent populations but decreases with distance around the ring

Answer 227

Ensatina eschscholtzii in Western USA. Ancestral population in N. Calfronia and moved south through different areas. Genetic analyses suggest that they form a superspecies that diverged in allopatry.

Answer 228

Greenish warbler in Asia, circular distribution around Tibetan plateau. Played back songs of males in different areas to see if the males recognised the species. SHOWED: - Male song recognition decreases with geographic distance - Males do not recognize each other’s songs in terminal populations

Answer 229

Parallel sexual selection across either side of the plateau for longer male songs: - one terminal = increased song length by increasing syllable length - other term = increased song length by repeating shorter syllables multiple times

Answer 230

Allopatric species because there was a deep genetic split in the ancestral populations. Still shows that reproduction isolation was enhanced by reduced gene flow around the ring.

Answer 231

Verbal ones.

Answer 232

Colonization events have special features that may lead to much rapid speciation due to adaptation to new habitats. Smaller, different genetic makeup (inbreeding maybe) in a new environment. Genetic drift can lead to fixation of novel alleles due to a restricted genetic sample of original population.

Answer 233

Found that one in flies that those in isolation could be achieved after a series of founder events but rarely for a single one. Small sample sizes in other studies count too.

Answer 234

Peripatric speciation on single oceanic islands. Presence of endemic species on oceanic islands whose closest relatives inhabit nearby continents is strong evidence.

Answer 235

Do not know if they are reproductively isolated.

Answer 236

If the island species is the sole representative of genus suggests that being isolated on that island causes a unique speciation event (not allopatric).

Answer 237

Cocos Island finch is the only Darwin's finch outside the Galapagos and the only member of its genus.

Answer 238

Peripatric speciation on archipelagos (group of islands).

Answer 239

Hawaiian archipelago has over 400 species of Drosophila. All descended from a single ancestor with more than 50% of species originated peripatrically with higher % for newer islands. Similar for cyanea plants.

Answer 240

As more islands forming, formation of new species (more possibility for colonization events).

Answer 241

Peripatric speciation in peripheral isolates (populations at an outside edge of the main species distribution).

Answer 242

1. Harder to detect on continents than islands 2. Sister species with abutting (touching) distributions but unequal range sizes can also result from vicariant speciation followed by reduction in range size

Answer 243

Clarkia biloba and C. lingulata are separated by 100m. Colonized by a population of C. biloba that speciated rapidly due to limited seed dispersal and some self-compatibility.

Answer 244

Changes in chirality (coiling) in land snails. Right and left coiling morphs are behaviourally isolated because they cannot copulate.

Answer 245

Comparative study showed that recently-formed allopatric taxa had very asymmetric range sizes, consistent with peripatric speciation.

Answer 246

Speciation between two populations with limited gene exchange.

Answer 247

Clinal speciation and stepping-stone.

Answer 248

A single species continuously distributed across a variable environment. Microadaptations to changes in environment that contribute to speciation (continuous along habitat).

Answer 249

Discrete populations having limited gene exchange.

Answer 250

Verbal and mathematical models.

Answer 251

Assumptions: - rates of gene flow - population sizes - genetic basis of reproductive isolation ex. small population, less gene flow, and strong genetic basis of reproductive isolation = parapatric speciation possible

Answer 252

Stepping-stones one because they are more isolated.

Answer 253

Experiment of houseflies Musca domestica. Two lines selected for different traits. Found migration between lines at 30% per generation and significant assortative mating (mating within their own line as opposed to the other one) after 38 generations. Can still have speciation with some limited genetic information exchange.

Answer 254

A pair of closely realted species with abutting (close) distributions.

Answer 255

Weak evidence as you can't distinguish between allopatric speciation.

Answer 256

Hybrid zones if you can exclude the possibility of previous allopatry.

Answer 257

Multiple pairs of related species with abutting distributions, like hybrid zones at ecotones. Better because you have multiple examples of it occuring.

Answer 258

Morphological or genetic incontinuities (changes) at ecotones, especially at hybrid zones. ex. little greenbul in Africa or lizard Anolis rouqet on Martinique

Answer 259

Shows a necessary step in the process as you're getting morphological change as the environment does change. Don't know if you continue over time if things will continue to diverge or need a barrier for speciation.

Answer 260

Observations of all stages of parapatric speciation in nature

Answer 261

Considered this evidence of parapatric speciation (see the whole range from diverged to not diverged) but could still be caused by allopatric speciation.

Answer 262

Jiggins and Mallet (2000) surveyed parapatric populations in several species and found every level of reproductive isolation: - from hybrid zones with random mating (complete gene flow) to boundaries maintained by strict reproductive isolation

Answer 263

Biogeographic and phylogenetic evidence of parapatric speciation in a small clade. Closely related “young” species with parapatric distributions.

Answer 264

Historical observations of speciation in parapatry.

Answer 265

Speciation in allopatry and range expansion (ranges separate, but got larger and touched each other) could cause this pattern AND hybridization (secondary contact if previously isolated) could also cause gene mixing making species appear “younger” (similar so diverged more recently than they are) than they are.

Answer 266

Evolution of heavy metal tolerance in plants growing near mines (more concentrated metals closer to mine, and plants developing adaptations). Sharp ecotone between contaminated and uncontaminated. Partial temporal isolation of flowering times provides some reproductive isolation (mate with tolerant ones) but still a lot of gene flow (NOT true species).

Answer 267

Hard to determine if truely right because even though they appear to be close environment and habitats, it's unsure whether or not they were separated once ago by barriers or range expansion.

Answer 268

The origin of an isolating mechanisms among the members of an interbreeding population (all occur within the same range).

Answer 269

Within the average dispersal distance or "cruising range" of a single individual.

Answer 270

He used a morphological species concept, but didn't understand reproductive isolation yet. He just believed that species would arise in sympatry to fill empty niches.

Answer 271

Realized it was very unlikely to occur based on genetics.

Answer 272

Antagonism between selection and recombination: - As selection tries to split apart a population, interbreeding continually breaks up gene complexes that produce reproductive isolation Ex. could break up genes for habitat fitness and habitat preference/NOT broken up could enhance speciation in sympatry

Answer 273

Coexistence: - Populations must develop sufficient ecological differences to coexist - Implies that selection should in part be driven by selection for ecological divergence NOTE: sexual selection doesn't cut it because even if you look different, you will be competing for the same food and resources

Answer 274

1. Disruptive sexual selection 2. Disruptive natural selection

Answer 275

Distribution of varying extreme individuals. Becomes concentrated on end points (biomodal). The intermediates will decrease.

Answer 276

More strongly in sexual traits than ecological adaptations. ex. african lake cichlids

Answer 277

The evolution of a single ancestral species into multiple descendant species that differ in their habitat, form, or behaviour. This process occurs when a population encounters new and diverse environments, leading to the development of different ecological niches.

Answer 278

No mechanism for the coexistence of new species in the same habitat.

Answer 279

Some success, but usually show unrealistic and restrictive assumptions.

Answer 280

Ecological divergence.

Answer 281

1. Discrete-habitat models 2. Continuous-resource models

Answer 282

Sympatric species that seek out different niches, are most fit in their own niches, and preferentially mate with members of their own niches. ex. insects that feed and mate on a specific host plant

Answer 283

1. Niche preference 2. Niche adaptation (more successful in preferred habitat) 3. Assortative mating (mating with certain members)

Answer 284

Not appropriate for many species: - sympatric species of African cichlids fish do not show dramatic differences in habitat (only look different)

Answer 285

Based on co-evolution of ecological traits and assortative mating. It splits populations into two sympatric groups, each using a different part of the resource distribution.

Answer 286

- Important resource (e.g. seed size) unimodally distributed – Ecologically-relevant trait (e.g. beak size) unimodally distributed – As population grows, frequency- and density-dependent selection favours individuals with more extreme values (larger and smaller beaks); because of competition for average size seeds/beaks – Splitting occurs if individuals with extreme traits prefer individuals with similar traits

Answer 287

- works best when individuals have innate preference for mating with other individuals having similar traits (large beak with large beak) - if mate preferences are not very strong, speciation takes so long that initial conditions probably change before speciation occurs (1 mill generations)

Answer 288

- change in mean beak size - when there was a severe drought, beak size increased afterwards to crack large seeds - new species arrived in a decade - over time, beak size decreases due to competition (average) from a larger competitor - new drought, decreased beak size even more - a short scale for variation makes sympatric speciation in the DD model seem less likely (no preferences for mates)

Answer 289

Yes, different beak sizes create different songs that attract mates.

Answer 290

- As the ends of the resource distribution become occupied, less competition for central resources, which should favor intermediate individuals – Could result in a continuum of interbreeding forms rather than discrete groups

Answer 291

Allopatric speciation

Answer 292

No, better to judge the likelihood of sympatric speciation based on laboratory experiments and evidence from nature.

Answer 293

- demonstrated reproductive isolation between selected lines that interbreed

Answer 294

They are "kill the hybrids" experiment where hybrids are removed in each generation. This leads to successful isolation, but it is not realistic.

Answer 295

- applied strong disruptive selection to flies moving up or down from a central chamber - reared apart but allowed to interbreed

Answer 296

After many generations, flies diverged in geotaxis and mating tests showed strong sexual isolation.

Answer 297

12 generations of disruptive selection for bristle number.

Answer 298

Flies showed complete assortative mating by bristle number (preferred individuals with same number of bristles).

Answer 299

Results couldn't be replicated in 19 future studies, most found moderate assortative mating.

Answer 300

By Rice and Salt and they found that individuals mate only with others who choose the same habitat -- "no gene" assortative mating maze.

Answer 301

1. Phototaxis (light or dark) 2. Geotaxis (up or down) 3. Chemotaxis (ethatnol vs. acetylaldehyde) Vials with each.

Answer 302

By only choosing flies that choose the extreme habitats to be allowed to breed: 1. Up/dark/acetylaldehyde 2. Down/light/ethanol

Answer 303

Only choose the flies that hatched early from habitat A (Up/dark/acetylaldehyde) and the flies that hatched late from habitat B (Down/light/ethanol).

Answer 304

Used mutations and chemical markers from a fly's eye colour.

Answer 305

Complete habitat isolation in 30 generations which meant all flies who had chosen each extreme environment were offspring of parents who had chosen that environment.

Answer 306

No evolution of complete habitat preference.

Answer 307

Offspring flies from extreme habitats continued to choose intermediate habitats but were considered lethal and discarded. When the flies were all put in a common environment they did not assortatively mate.

Answer 308

That habitat isolation can evolve if selection is strong and assortative mating is a byproduct of habitat choice. Strong disruptive selection appears necessary but not sufficient for sympatric speciation by itself.

Answer 309

1. Because it's easier than sympatric speciation. Selection or drift acting on geographically isolated populations will eventually produce isolating barriers. 2. There is also strong and persuasive evidence for allopatric speciation. 3. Many opportunities for geographic isolation; over the past 2 million years, there has been 20 major glacial advances and more frequent cycles of temperature changes

Answer 310

1. Species must be largely or completely sympatric 2. Must have reproductive isolation, preferably of genetic origin 3. Must be sister groups (closest relative) 4. Biogeography and evolutionary history must make allopatry very unlikely

Answer 311

All on a common branch, thus diverging/evolving from a common ancestor.

Answer 312

When looking at a distribution, they overlap; however, visiting their locations in person, will demonstrate a small geographic isolation.

Answer 313

If a small monophyletic group was confined to a small isolated habitat, it would be convincing.

Answer 314

Endemic Coleptera and Orthoptera on St. Helena once thought to have speciated in sympatry, but since the species are all flightless, this means they could have speciated microallopatrically.

Answer 315

Could have speciated microallopatrically OR on small islets that were connected to mainland during Pleistocene.

Answer 316

Suggestion of allopatry because of negative correlation between endemism and mobility (less endemic, more mobile they are). The group wasn't endemic, so multiple colonizations could have occured.

Answer 317

No sister species on isolated islands, so they could not separate or diverge in sympatry.

Answer 318

Some lakes contain closely related fish differing in morphology, behaviour, habitat, or life history. ex. threespine sticklebacks in same lake but have different vegetation, morphology, and assortative mating

Answer 319

Most likely 15,000 years ago when lakes in N. America ad Eurasia were formed from the last glaciation.

Answer 320

1. Lakes connected to rivers and the sea, which could allow from multiple invasions from allopatric taxa 2. Gene exchange after secondary contact (hybridization) can yield misleading conclusion that the fish are sister taxa; hybrids have intermediate genes (need to use nuclear DNA instead of mtDNA)

Answer 321

Arctic charr in Lake Galtabol, Iceland - limnetic and benthic morphs are more closely realted to each other than taxa in four nearby lakes - genetic similarity does not reflect current hybridization: share no alleles at one of six nuclear loci and strongly differentiated at other loci

Answer 322

Rift lake = victoria, malawi, and tanganyika Tiny crater lakes = barombi mbo and bermin (much smaller and isolated, so fewer species)

Answer 323

Quite high, some higher than the larger rift lakes.

Answer 324

1. Hard to envision geographic barriers allowing formation of hundreds of species in only 2 million years 2. Speciation evidence has also occurred in limnetic and deep water forms less likely to encounter geographic barriers (not in open water) 3. Movement between habitats may prevent allopatric speciation (no walls separating habitats) 4. Closely related species differ more in colour than morphology and habitat use 5. Some pelagic (open water) species show no genetic structuring across Lake Malawi; fish are so mobile that allopatry not possible (don't cluster together genetically; huge intermixing population) 6. Monophyletic groups of pelagic species show that speciation occurred in pelagic ancestors

Answer 325

1. Levels of all three major lakes have risen and fallen repeatedly, creating isolated small lakes 2. Many species have highly localized ranges and shorelines have diverse habitats (rocky, sandy, swamps, bays, rivers) 3. Habitat specificity can reduce gene flow 4. Genetic patterns sometimes mirror fragmentation of lakes (cluster genetically to past areas of lakes) 5. Littoral fish have limited migration but occasionally colonize new habitats, promoting allopatric or parapatric speciation 6. Some pelagic species return to littoral zone for spawning which could cause allopatric speciation by habitat segregation 7. Some allopatric populations evolved behavioural isolation during periods when there were barriers to dispersal

Answer 326

More convincing in the small crater lakes because: - Fish differ more in feeding habits and morphology relating to diet – Little sexual dichromatism – Sister species and no evidence of hybridization – Size and formation of lakes suggests no allopatry (not connected to other lakes in the past; formed in tops of old volcanoes) – Meet the four criteria for sympatric species

Answer 327

Host-specific parasites occupying different host species could be considered islands.

Answer 328

Parasites that occupy different parts of the same host species, so they exist within the same geographic range. ex. lice in birds occupying different feathers or even different parts of the same feather

Answer 329

No since genetic studies show similarity.

Answer 330

Different fig wasps had different ovipositer lengths depending on the type of figs they were parasites too. Also, there was temporal segregation (different fig wasps breed at different times of the year).

Answer 331

Since the fig wasps and different adaptations happened on an island chain (Melanesian).

Answer 332

Involve two different races of species living on different host plants in the same area (not true species, evidence that speciation is occuring).

Answer 333

Apple maggot fly that used both apples (introduced by colonizers) and hawthorns (original host; native) as hosts in the US.

Answer 334

No, recent genetic evidence suggests that the apple race might have descended from an allopatric hawthorn race rather than the original one in the area.

Answer 335

Already diverged. They are species that live on different hosts and show little gene flow. ex. treehoppers

Answer 336

Each of six species inhabits a different species of tree and they are reproductively isolated.

Answer 337

No, genetics show that they are not sister species. Referring to the ones that differ in colour and habitat.

Answer 338

Different times of breeding or flowering.

Answer 339

Even though the two species breed at different times, they are not sister species.

Answer 340

Periodic cicadas that breed in 13 year vs 17 year cycles shows influence of rapid changes in life cycle of reproductive isolation. NOTE: cannot exclude biogeography

Answer 341

Calculate degree of range overlap across groups of closely-related species.

Answer 342

Changes in range over time should lead to slightly increased overlap.

Answer 343

Range overlap should decrease over time (since speciation occurred during complete range overlap).

Answer 344

In many animals (mammals), range overlap almost always increases over time, which is consistent with allopatric speciation.

Answer 345

Difficulties in determining close relatives. For example, two very closely related species of chipmunk show little to no divergence with large range overlap based on mtDNA (sympatric). However, when using nuclear DNA, this pattern disappears.

Answer 346

Pocket gophers showed perpetual allopatry (there is no increase in range overlap with time). No matter how long they have diverged, there is no evidence for sympatric speciation.

Answer 347

For kangaroo rats, do not tend to see an increase in overlap over time. A point shows that the closest relative have a high degree of overlap.

Answer 348

Charles Darwin and Ronald Fisher

Answer 349

Just recently

Answer 350

Prezygotic barrier

Answer 351

Habitat isolation, pollinator isolation, and temporal isolation.

Answer 352

Occurs when spatial separation of species is based on biological differences and reduces gene flow between taxa.

Answer 353

From genetic differences in fitness based on habitat use not geographic isolation.

Answer 354

A species' inability to use another species' environment (can exist in sympatry and adaptations arise). Competition forces species to use different niches when in sympatry and in animals, the ability to seek out habitats for which they are best suited.

Answer 355

Limits reproductive encounters between conspecifics and heterospecifics.

Answer 356

Reduces relative amount of heterospecific pollen reaching the stigma.

Answer 357

Individuals fail to encounter heterospecifics and sometimes even conspecifics during the breeding season.

Answer 358

Members of two species occupy same general area but reproductive encounters reduced by adaptations to/preferences for ecologically different parts of this area.

Answer 359

Square-tailed drongo (Dicurus ludwigii) and the fork- tailed drongo (D. adsimilis). D. L occupies forest areas and the D. a occupies open areas. May occur closely (50 yards) but won't mate.

Answer 360

Microspatial isolation of six species of goldenrod along a moisture gradient on a prairie slope. One species prefers more dry soil and the other wet soil, so less likely to encounter during breeding season.

Answer 361

Two taxa cannot interbreed because their habitats are allopatric (habitats farly isolated from on another; not a geographic barrier). This isolation is important in parasites and host-specific insects that are dependent on allopatric hosts.

Answer 362

Ophraella chrysomelid beetles are host-specific: * Some allopatric species cannot survive or oviposit (lay eggs) on each other’s hosts - Shows genetic basis for difference

Answer 363

Two species may be largely allopatric but their ranges may overlap in an area containing patches of both habitats.

Answer 364

Crickets Gryllus pennsylvanicus and G. firmus are largely allopatric. G. pennsylvanicus prefers loamy soils while G. firmus prefers sandy soils. In places where both habitats exist, each species is restricted to its preferred soil type.

Answer 365

1. Spatial separation between members of different species is, on average, larger than between members of same species 2. This spatial separation impedes gene flow during the period when both breed simultaneously 3. Reduced gene flow occurs solely through decreasing the chance of cross mating or cross pollination 4. Spatial separation is based on genetic differences between species

Answer 366

Transplant and removal experiments

Answer 367

If cross-pollination or hybridization increases when individuals moved closer together, then they are habitat isolated (physically separation enough to keep them from mating).

Answer 368

If removal of one species from a habitat causes another species to expand into that area, microspatial isolation enforced by interspecific competition.

Answer 369

Allopatry could be caused by habitat isolation or could be unrelated.

Answer 370

Transplant or laboratory experiments

Answer 371

If allopatry enforced through habitat isolation, species transplanted to each others’ habitats, or grown under conditions favourable to other species, should not thrive.

Answer 372

Drosophila sechellia lives only on Seychelle islands * Close relative D. mauritiana on Mauritius * D. sechellia feed and breed only on rotting fruits of Morinda citrifolia, which are toxic to other Drosophila * Differences in D. sechellia oviposition preference, larval survival, and adult survival is genetic * Other Drosophila occupying Seychelles would presumably show complete habitat isolation (would not come in contact with one another because of food preference)

Answer 373

No, not a lot of data showing that spatial isolation reduces gene flow. For instance, in the goldenrod, even though they are separated in microhabitats, pollinators can move and transfer pollen between.

Answer 374

Studies in nature combined with lab studies.

Answer 375

Two subspecies of sagebrush (Artemisia tridentata tridentata and A. tridentata vaseyana) segregated by altitude in Utah. When the subspecies are transplanted in common garden experiments, each species has higher fitness in soil from its native habitat.

Answer 376

Studies of Horkelia plants in California by Clausen et al. 1940. H. fusca lives above 1400m while H. californica and H. cuneata live along the coast below 1000 m. After one generation in common gardens (green house, which is a controlled habitat), species were transplanted to various habitats. H. fusca showed poor viability and little flowering at low elevations while the low-elevation species did not survive at higher elevations.

Answer 377

The apple maggot fly Rhagoletis pomonella feeds and breeds on apples and hawthorn, while R. mendax mates and oviposits only on blueberry. Hybrids are readily produced in field cages but are never found in the field where they co-occur in Michigan.

Answer 378

Habitat isolation in plains leopard frogs (Rana blairi) and northern leopard frogs (R. pipiens). Where their range overlaps in Nebraska, R. blairi breeds in turbid silty streams while R. pipins prefers clear streams.

Answer 379

Habitat displacement in birds: Closely-related species occupy more divergent habitat when sympatric – Size-related habitat segregation in Amazonian birds enforced by competition with body size (Robinson and Terborgh 1995) – Congeneric birds (more closely related) are often altudinally segregated in New Guinea (Diamond 1973) * Driven by competition since species expand altitudinal range when congeners are absent

Answer 380

Evidence in sunfish (Lepomis), rockfish (Sebastes), and damselfish (Stegastes) through artifical removal experiments. Other species take over the habitat when one species is gone, but before, they have own separate habitats

Answer 381

Can show whether habitat expansion accompanies the absence of a competitor.

Answer 382

Invasion of new environments can produce almost any form of reproductive isolation.

Answer 383

Habitat isolation evolved first in greenish warblers, prey size and feeding method appeared later.

Answer 384

Obligate mutualisms in which plants and insect pollinators have evolved and speciated in tandem (cospeciation).

Answer 385

Initial stages of habitat isolation seen in adaptive differences in habitat use among populations of a single species. Ex. plants that are locally adapted to temperature or soil chemistry or heavy metals near mines

Answer 386

Host-specific mating (mate and eat on that host, so fully separated during mating period) Ex. parasitic chewing lice Speciation likely allopatric since they are flightless and their entire life cycle is on a single host.

Answer 387

Each pocket gopher species have a species of chewing lice. The closest relative of pocket gopher species share a pair of relatives of chewing lice. Show divergence of both at the same time.

Answer 388

Similar findings in seabirds and their lice, including some sympatric species of seabirds with distinct species of lice. Swiftlets and their lice. That parasite evolution followed host evolution (but why do lice have to diverge).

Answer 389

If two species diverge in sympatry, habitat isolation through niche differentiation can be a driving force, reduces competition. If sympatry results from secondary contact, reinforcement or competition could lead to habitat isolation. ex. warblers and niche partitioning on trees

Answer 390

1. Drosphilia simulans/D. sechellia show habitat isolation based on food preferences: adult tolerance shows 5 or more genes, larval for three or more, adult oviposition showed 2 or more, and rate of egg production showed 4 or more genes 2. Acyrthosiphon pisum pisum alfalfa versus clover race on (p. ahpids) different host plant feeding five genes responsible 3. Mimulus guttatus (monkey flower) populations have one gene in copper tolerance NOT a lot of genes required for habitat isolation

Answer 391

Gene flow between angiosperms is reduced because different species use different pollinators. - hummingbirds would have flowers with long tubes

Answer 392

If closely-related sympatric species of animal-pollinated plants bloom at the same time and can produce viable hybrids in a greenhouse, but none are found in the wild. Pollinated by different species.

Answer 393

No pollinator specificity as the number of visits by a specific pollinator species is not correlated with pollination ability.

Answer 394

Dye pollen grains: keep track on plant species where the pollen grains end up. - a study in red and white campions (Silene dioica and S. latifolia) using dyed pollen showed that pollinator isolation is about 0.45

Answer 395

Fig and fig wasps, yucca, and yucca moths. One-to-one relationship between host and pollinator species. ex. 750 Ficus fig species pollinated by a similar number of Agaoinidea wasps (each fig species own wasp species for pollination)

Answer 396

Both individuals benefit in an interaction: plants gets a pollinator and insect gets a breeding site.

Answer 397

Mimulus lewisii (pink) pollinated by bees and M. cardinalis (red) pollinated by hummingbirds. Strength of isolation based on pollinator visits is 0.98. Can be crossed easily in the greenhouse but only 2 of 2000 seeds collected in the wild produced hybrids.

Answer 398

Pollinator isolation produced by differences in flower color and nectar volume.

Answer 399

Thought to be unimportant but several studies show pollinator isolation. General observation that closely-related sympatric species either use different pollinators or place pollen in different parts of the pollinator’s body.

Answer 400

Two broad comparative studies show strong associations between species diversity and animal pollination or traits associated with animal pollination (in groups where flowers are pollinated by animals there tends to be more species). – Pollinator isolation may have been instrumental in angiosperm speciation

Answer 401

Easily in allopatry: - Novel pollinators in new areas – Or similar species of pollinators but in different proportions – Extinction of a local plant or pollinator – Change in pollinator preference due to change in visual or chemical environment could be followed by flower evolution to match preference

Answer 402

Incipient stages of pollinator isolation in the African orchid Satyrium hallackii. Subspecies ocellatum lives in grasslands and is pollinated by hawkmoths. Subpspecies hallackii lives on the coast and is pollinated by carpenter bees. Corresponding changes in flower spur length (the part with nectar in it). Speciation in process.

Answer 403

In sympatry because how can reproductive isolation evolve when at least one other species – the pollinator – is a key player? (changes in both).

Answer 404

In monkey flowers, genes affect 12 floral traits involved in pollinator isolation (colour, shape, etc.). In Aquilegia species, 1 gene in nectar spurs, 1 gene is shape of spurs, and 1 gene in flower position. NOT much genes needed to control the change.

Answer 405

Gene flow impeded because different species breed at different times.

Answer 406

Different breeding season or spawning season.

Answer 407

Different flowering periods, timing of pollen shedding, timing of ovule receptivity.

Answer 408

Must show that eliminating the barrier could produce viable and fertile hybrids (breed at the same time). - two types of pink salmon breed every other year - when in the lab, on the same cycle, they can breed together

Answer 409

Tropical Atlantic corals Montastraea annularis and M. franksi. Release gametes synchronously into the water column over 15-30 minutes. Peak spawning time of two species is 1.5-3 hours apart. Artificial fertilizations produce viable hybrids. Spawning time between M. annularis and M. faveolata is not offset because they are more distantly related and their gametes are incompatible. - important for closely-related species that don't have additional isolating mechanisms

Answer 410

General consensus that temporal isolation is not very important in animals. ex. in many birds and mammals, timing of reproduction is tied to food availability and photoperiod – little option for temporal segregation

Answer 411

In plants, habitat or pollinator isolation may be more important than temporal isolation.

Answer 412

In already-isolated species.

Answer 413

In animals, local differences in food availability and temperature (not as common).

Answer 414

In plants, abiotic cues for flowering time such as photoperiod, temperature, and moisture.

Answer 415

In plants, sympatric species can diverge in flowering time by reproductive character displacement. To reduce competition for pollinators, to prevent hybrid inviability or sterility, or to avoid clogging stigmas with foreign pollen.

Answer 416

Through reproductive character displacement (any trait that makes plants or animals less likley to mate) and reinforcement (natural selection that trys to enhance mechanisms to keep species apart by selecting against hybrids).

Answer 417

In animals, reinforcement increases temporal isolation to reduce hybridization or reduce interference between mating calls. ex. spring field cricket and fall field cricket that call and mate at different times OR genus Rana of frogs have the sympatric populations breeding at different times (3)

Answer 418

Instantaneous shift in breeding season. ex. pink salmon that breed in alternate years

Answer 419

Lacewing species, two genes are responsible to photoperiods (day lengths) to trigger mating at different times of a year.

Midterm 1 - Lectures Flashcards

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