Final Exam

Question 1

What are some of the factors that affect yearly populations?

Answer 1

-Major storms/natural disasters (e.g. Hurricanes, Volcano eruptions)
-Unpredictable climate shifts (unseasonably hot/cold/wet/dry)
-Disease
-Predation
-Acute habitat loss/destruction (man made or natural such as fires, deforestation)

Question 2

Are birds able to rebound after population crashes? Explain boom and bust.

Answer 2

Bird populations have capacity to rebound and even increase, given more favorable conditions in future years.
-Short-tailed Albatrosses were declared extinct in 1949 after a volcanic eruption on a Japanese Island in 1939 and 1941.
-In 1954, six pairs of young survivors that had been out to sea returned to breed.
-A total of three young albatrosses were hatched and the population had increased to 1,840 birds by 2005.

Texas quail, especially the Scaled Quail, experience boom and bust years that correspond to rainfall

Question 3

What is mean generation time?

Answer 3

when children produce grandchildren

Question 4

What are the four major attributes that specify the performance of the average bird in a population

Answer 4

1)Age at which the bird first reproduces
2)Its fecundity (# of young it fledges each year)
3)Survival of its young
4)Its longevity (lifespan) as an adult

Question 5

What primary forces limit the size of bird populations? Bold the #1 determinant of population size

Answer 5

Habitat
Food
Climate
Disease
Predation

Question 6

What is regulation? How does this affect population size?

Answer 6

Regulation: the effects of population density on population size.
-Low population densities tend to rebound/grow
-High population densities tend to reduce themselves

Density-dependent

Question 7

What are irruptions? Why does this happen?

Answer 7

are sudden, sharp increases in a population

This is common in birds from arctic and subarctic regions that rely on food supply that shows cyclical abundance.
Lemmings (a small rodent found in the tundra) will exhibit cyclical abundance cycles.
Snowy Owls will cache an abundance of lemming carcasses for chicks, resulting in high nesting and fledging success.
Young Snowy Owls will then disperse the next year, reaching more southerly regions.

Question 8

How do predators and disease affect bird populations?

Answer 8

Natural predators are a major source of annual mortality among birds, especially nestlings, incubating females, or weak/sick young birds in their first year.
In past 500 years, half of island species extinctions were caused by introduced predators and diseases (the rest by human exploitation and habitat destruction).
Removal of top predators such as coyotes and wolves has actually increased nest predation by thriving mid-size species (fox, raccoons, squirrels, cats, dogs, snakes, etc.)

Parasites include:
-Parasitic worms and blood parasites
-Ticks
-Mites
-Bedbugs
-Blowflies
Other:
-Bacterial infections
-Viruses (such as West Nile and Avian Flu)

Question 9

Social forces are density-(dependent/independent) factors.

Answer 9

Dependent

Question 10

What are the three stages of habitat occupation?

Answer 10

1) Primary habitat fills up
2) Surplus birds move to suboptimal habitat (waiting for vacancies in primary habitat)
3) Remaining birds become floaters (waiting for vacancies in either habitat)

Floaters are non-territorial birds whose movements exceed those of territorial birds (male or female)

Question 11

What factors led to the decline in game bird populations?

Answer 11

-Loss of Habitat (specifically wetland, prairie)
-Looser hunting regulations

Question 12

What is a population bottleneck?

Answer 12

Reductions in population size and reduced genetic diversity

Question 13

How are birds used as sensitive indicators of environmental health?

Answer 13

Canaries were used in mineshafts to detect presence of coal-mine gases.
Birds interacting with environment as predators, prey, pollinators, and seed dispersers make them pivotal players in ecosystem dynamics.
Worldwide, we often look to birds as indicators of biodiversity and barometers of ecosystem health.
Predators such as raptors at the top of the food chain concentrate toxins in their bodies.
In the 1950s-1970s, Eagles, Ospreys, and Peregrine Falcons were either killed directly by organochloride pesticides or had sterility or nesting failure due to weak eggshells.

Question 14

How do we track bird populations?

Answer 14

How do we track bird populations, aside from what is reported by hunters for game birds?
Citizen Science Programs allow volunteers to help track populations of all birds (also trends and changes in environment):
-Christmas Bird Count
-Breeding Bird Survey
-Project of Cornell Lab of Ornithology/ National Audubon Society
-Also “Great Backyard Bird Count” and “Feederwatch” have become global efforts thanks to social media.

Question 15

What is a species? What is characteristic about them?

Answer 15

Species are the primary units for describing and analyzing biological diversity.
Each species has a characteristic size, shape, color, behavior, ecological niche, and geographical range.
Genetic differences also help us to define species and to track their evolutionary history.
Mitochondrial DNA sequencing reveals 260 species of North American birds.
Different species in the same genus average 7.9% genetic divergence

Question 16

The average percentage of genetic divergence within a species is just ____%.

Answer 16

0.4%

Question 17

What is the biological species concept?

Answer 17

Biological species are genetically cohesive groups of populations that are reproductively isolated from other groups.

Question 18

What is assortive mating?

Answer 18

Assortative mating is mating of like individuals.

Question 19

What are the phylogenetic and evolutionary species concepts?

Answer 19

focus on defining species as distinct evolutionary lineages.

Question 20

What is allopatry? How can this lead to reproductive isolation?

Answer 20

Evolving in geographical isolation

Allopatric speciation model explains the origin of most species of birds.
Sister populations separated and isolated from each other diverge genetically.

Question 21

What is the first step towards speciation?

Answer 21

Reduced/Halted gene exchange with sister populations first leads to evolution of subspecies, and is the first step toward speciation.

Question 22

What is sympatry?

Answer 22

Divergence due to ecological adaptation and/or sexual selection precedes sympatry or sympatric speciation.
Sympatry is co-existence in overlapping geographical areas without interbreeding.

Question 23

What is secondary contact? What are the potential outcomes?

Answer 23

Secondary contact: is the interaction of divergent sister taxa.
Secondary contact tests their reproductive, ecological, and behavioral compatibility.
Potential outcomes:
1)Species may practice strict assortative mating, maintaining reproductive isolation and remain distinct species.
2)Species might hybridize and blend with each other.

Question 24

What is natal dispersal? How does it connect local populations by gene flow?

Answer 24

Natal dispersal: movement of young birds from sites where they hatched to sites where they breed.

Gene flow: the movement and incorporation of genetic alleles among local populations due to dispersal.

Large natal dispersal distances unite geographically diverse populations
Small natal dispersal distances increase genetic isolation of local populations
Small natal dispersal distances favor evolutionary divergence

Question 25

What is a cline?

Answer 25

how much the local compositions of genes change from site to site. Cline depends on gene flow due to natal dispersal, and may be: -Static -Dynamic Clines are especially conspicuous in birds that have simple genetic color morphs.

Question 26

What is hybridization? How is this so successful in birds?

Answer 26

More than 10% of bird species are known to hybridize, or, pair and successfully reproduce with at least one other species. Small genetic changes cause sterility in male fruit flies but not in birds. Birds retain potential for successful hybridization through surprisingly high levels of genetic divergence and retained genomic compatibility. Successful hybridization of birds is not limited to closely related or sister species and can even hybridize with different genera. Wood warblers, ducks, pheasants all exhibit some hybridization within genera.

Question 27

What is Haldane’s rule?

Answer 27

Some bird hybrids exhibit sterility Almost all hybrids of the Eastern Meadowlark and Western Meadowlark are sterile. Hybrids appear normal and healthy, but usually produce infertile eggs when paired in captivity with an Eastern Meadowlark or Western Meadowlark. Thus, the two meadowlarks remain distinct biological species. Haldane’s rule: sex with two different sex chromosomes tends to be sterile more often than the sex with two of the same chromosomes.

Question 28

What is the importance of hybrid zones? What are the two theoretical models that support hybrid zone stability?

Answer 28

Ornithologists have long used the extent of hybridization between different populations to determine whether two populations actually belong to the same species. -Separate biological species status is given if no hybrids exist and complete reproductive isolation is determined OR if hybrids are infrequent and less viable OR if zones of contact and hybridization are narrow and stable. -If hybrids are abundant and breed freely with parental types in zones of overlap, then the two populations are considered the same biological species. Supported by two theoretical models: 1)The bounded superiority model (Moore 1977) proposes hybrid zones coincide with intermediate ecological or climatic conditions where hybrids are equally or better adapted than their parents. 2)The dynamic equilibrium model (Barton and Godfrey 1985) proposes a stable hybrid zone is a population sink of inferior hybrids produced relentlessly by immigrants from adjacent, large, pure populations.

Question 29

What can be the driving force of evolutionary change if followed by the evolution of new traits that support it?

Answer 29

The capacities of birds to develop new, learned behaviors contributes to the process of speciation. Behavior, rather than environment, can be the driving force of evolutionary change if followed by the evolution of new traits that support the behavior. Thus, traits such as bill morphology, song, and plumage play a significant role in species recognition and ultimately mate choice (via sexual imprinting and sexual selection).

Question 30

What are more diverse, tropical or temperate habitats? Why?

Answer 30

Latitudinal gradients are among the best-documented patterns in avian ecology Tropical habitats have more diverse communities than those in the temperate zone in both richness and diversity. and more varied food resources. ●More varieties of seeds, fruits, and nectars ●Greater diversity of insect sizes ●Greater number of small reptiles Ornithologists used to think there was more forest diversity and complexity contributing to greater diversity in the tropics. Studies now show that tropical species of birds tend to use a narrower range of habitats and more specialized foraging behaviors than temperate zone species. Greater ecological specialization leads to: Loose packing of species in local communities Small geographical distributions Greater Species Richness Reduced abundance of most species?

Question 31

Differentiate alpha, beta, and gamma diversity

Answer 31

Alpha diversity: # of species coexisting over a single point or site Beta diversity: extent to which species composition changes in different habitats (elevation gradients, different stages of succession in forests) Gamma diversity: total # of species occurring in a region

Question 32

What are trophic levels? Ecological niches?

Answer 32

The species in a community can occupy different trophic levels (feeding levels). Trophic levels range from insect-eating warblers to the hawks that eat them and from plankton eaters to fish eaters. Each species has its own requirements called its fundamental ecological niche.

Question 33

How does food availability affect species diversity?

Answer 33

Availability of different kinds of food Some alkaline lakes in Africa only contain a few resources (i.e. blue-green algae and zooplankton that feed on the algae). Although these resources are abundant and sustain millions of flamingos, it is one of the least diverse breeding bird communities in the world. The reverse can also be true: lots of different types of food allow for high alpha diversity in tropical forest birds, but species density can be very low. In one Amazonian community, more than ⅔ of the bird species had population densities of less than three breeding pairs per square km.

Question 34

How does seasonal resource availability affect bird community composition? What two characteristics of birds make this possible?

Answer 34

Virtually all bird communities have resident and non-resident species. Residents stay put and accommodate monthly changes in climate and food availability Non-residents are seasonal specialists that take advantage of predictable periods of regional food abundance. What two characteristics of birds make this possible? Highly mobile and migratory behavior

Question 35

How do ephemeral resources affect bird community composition?

Answer 35

Ephemeral resources attract opportunistic species. Temporary assemblages of highly mobile birds may last hours, weeks, or years. Flocks of seabirds over a shoal of fish, for example, are brief in duration (minutes or hours) and highly variable in species composition. Assemblages of hummingbirds and sunbirds at flowers feature high turnover of both individual birds and species during the brief blooming periods of days or weeks.

Question 36

How do climatically extreme environments impact adaptations?

Answer 36

Climatically extreme environments, like deserts or the arctic/antarctic, require physiological adaptations that limit which species can occupy them. This extreme environmental filtering means just a few lineages of birds have the adaptations to live in these regions. Are there filtering effects in less extreme climates on community composition? Communities in more benign environments tend to be from more diverse lineages and structured by more biotic interactions such as competition.

Question 37

What is intraspecific competition?

Answer 37

Interspecific competition arises when one bird’s use or defense of a resource makes that resource less available to other birds (coexisting species of birds vie for the same limited resource). Resource/Niche partitioning is one adaptation found to have evolved in virtually every system. Coexisting species from the same foraging guild (a group of species that eat the same resources in the same times and places) almost always differ in some aspect of their foraging ecology or size.

Question 38

What is a foraging guild?

Answer 38

a group of species that eat the same resources in the same times and places

Question 39

Differentiate between interference competition and exploitative competition?

Answer 39

Interference Competition is a type of interspecific competition that is an overt aggressive displacement of other species Exploitative Competition is a type of interspecific competition that depletes limited resources, depressing another species survival or breeding success

Question 40

Bills of various species of finches are (_less_/_more_) alike when they do not live together, and show (_lessened_/_enhanced_) differences when they do coexist.

Answer 40

More, enhanced

Question 41

How do introduced predators reduce community diversity?

Answer 41

Introduced predators have greatly reduced community diversity on many islands. Video: Brown Tree Snakes in Guam Nest predation can also help maintain or promote community diversity by preventing any one species from becoming too dominant.

Question 42

How do parasites and pathogens affect community composition?

Answer 42

Parasites and pathogens can affect community composition, especially when there in not a long history of coevolution between parasites and their hosts. Brown-headed cowbirds may reduce or eliminate species with no evolved response to brood parasitism. Diseases such as avian malaria in Hawaii or other islands may result in reductions in community diversity. Video Continental birds, however, may have more effective immune systems and the capacity to recover from severe losses. Invasions of continents by new diseases such as West Nile Virus only cause temporary changes on communities.

Question 43

What are mutualistic interactions?

Answer 43

Mutualistic interactions can promote community diversity. Examples include: ●Plants and their pollinators and fruit dispersers ●Woodpeckers and their trees Woodpeckers nest excavation behaviors open up opportunities for secondary cavity nesters to utilize trees and habitats not otherwise suitable.

Question 44

What are metacommunities?

Answer 44

History and biogeography play major roles in dictating community composition. Community dynamics have been extensively studied on islands, since they are separate and distinct, and more easily studied. Metacommunities are defined as communities connected by dispersal events. Ongoing cycles of island colonization (immigration) and extinction by birds affects the community composition.

Question 45

What is the Equilibium Theory of Biogeography?

Answer 45

The Equilibrium Theory of Biogeography states that the number of species present on islands theoretically reaches a balance between gains due to immigration (colonization) and losses due to extinction. Extinction rates: -Higher for a smaller islands (fewer resources support fewer birds, higher proportion of casualties related to natural/man-made disasters due to small size). -Lower for a larger island (more resources to support more birds, lower proportion of casualties related to natural/man-made disasters due to larger size). -Higher for more distant islands (fewer birds likely to arrive from mainland “rescue effect”) -Lower for closer islands (more birds likely to arrive from mainland “rescue effect”) Immigration rates: -Higher for larger islands (more resources/space can support more birds) -Higher for closer islands (easier and faster to find from mainland) -Lower for smaller islands (less resources/space to support birds) -Lower for distant islands (harder and longer to find from mainland) Equilibrium takeaways: Small, isolated islands (more distant) have the smallest equilibrium number of species. Large islands near continental source areas have the highest species equilibrium.

Question 46

Differentiate between the extinction and immigration rates of small, large, close, and distant islands.

Answer 46

Question 47

What is the IUCN Red List? How many species are globally endangered? Globally vulnerable? Which order is considered to be most at-risk?

Answer 47

More than 10% of the world’s birds species are endangered or vulnerable. In the U.S. about half of bird species are declining. Species that can adapt to man-made environments are increasing. Term to know: Red List: a species risk for extinction, determined by the International Union for Conservation (IUCN).

Question 48

What species are decreasing? What species are increasing?

Answer 48

Species that are Decreasing: -Neotropical Migrants -Grassland and Savannah Species -Migrant Shorebirds -Seabirds of the Southern Hemisphere -Songbird species with restricted ranges ⅓ of North American bird species need urgent conservation action, especially grassland species like the Eastern Meadowlark, Loggerhead Shrikes, Greater Prairie Chickens, and quail. Species that are increasing: Common Pigeons Common Starlings House Sparrows Canada Geese Ospreys Monk Parakeets Red-tailed hawks Cooper’s Hawks Turkey Vultures American Crows

Question 49

What percentage of North American bird species need urgent conservation action? Which species need it most?

Answer 49

⅓ of North American bird species need urgent conservation action, especially grassland species like the Eastern Meadowlark, Loggerhead Shrikes, Greater Prairie Chickens, and quail.

Question 50

How do expanding human populations continue to threaten native bird populations? What is the primary threat?

Answer 50

Expanding human populations continue to threaten native bird populations. Hunting Overfishing Commercial pet trades Pesticide/chemical contaminants Predation (introduced predators and pets, mesopredators) Collisions with cars, windows, towers Habitat distruction Examples: -Replacement of virgin rainforest by pastures and coffee or banana plantations -Conversion of rich grasslands into crops -Draining of wetlands -Urban sprawl Tropical rain forests cover less than 7% of earth’s landmass but contain 66% of all species. 50 million acres annually are destroyed.

Question 51

Tropical rainforests cover less than ______% of the Earth’s landmass but contain ______% of all species.

Answer 51

7% 66%

Question 52

The wholesale slaughter of wild birds and the expansion of human civilization accounts for over ______% of the known historical extinctions. Why? Give an example of some of the birds that have gone extinct because of humans.

Answer 52

90% Video: The Dodo (lower left) Passenger Pigeon (right, below)

Question 53

What is the goal of conservation? What do current conservation initiatives focus on?

Answer 53

Goal of conservation is to stop current declines and prevent further extinctions. Current conservation initiatives focus on: -Habitat preservation and habitat restoration Regulations, Top left: Important Bird Area (IBAS) and flyways; right: Wood Duck (declines due to habitat loss, hunting) Lower Left: Peregrine Falcons (extreme losses due to DDT); lower right: Atlantic Puffins (a social species hunted for birds and eggs had been extirpated from Maine by 1880s)

Question 54

What is hacking?

Answer 54

Hacking: breeding young birds in captivity and releasing them into the wild to rebuild a free-living population.

Question 55

What are extinction hot spots?

Answer 55

Hot spots: places under threat in the world that have the greatest concentration of biodiversity (defined by largest total # of species, most threatened/endangered, and the most endemic species)

Question 56

Short generation times:

Answer 56

early age at first reproduction combined with short lifespan.

Question 57

Carrying capacity:

Answer 57

Maximum population capacity supportable by the environment.

Question 58

Life tables:

Answer 58

summarize vital statistics of age-specific survivorship and fecundity.

Question 59

Limitation

Answer 59

the ceiling on population growth - Density-independent

Question 60

Species richness:

Answer 60

the number of coexisting species in a community

Question 61

Community diversity:

Answer 61

extent to which communities are dominated by just a few or by many different species