Chapter 3 & 4 Flashcards
Define morphology and two issues with the morphological species concept.
outward appearance (shape, structure, colour, pattern) and the form and structure of the internal parts
(1) variation within a species
(2) Difficulty determining what variation is within and which is outside of the species
Who proposed that species are reproductively isolated from other species and what is the limitation of the biological species concept?
Theodosius Dobzhansky
and expanded by Ernst Mayr
(1) fossils and asexually reproducing organisms cannot be tested
What type of organism is the morphological species concept successful in identifying species?
bacteria
Describe the ecological species concept
Species are defined in terms of their ecological niches, focusing on unique adaptations to particular roles in the biological community
What are some Prezygotic reproductive barriers that differentiate species in the biological species concept?
species have different habitats (habitat isolation) or breeding/flowering seasons (temporal isolation). Behaviour differs and results in no sexual attraction (behavioural isolation).
Structural differences in sexual organs prevents copulation/pollen transfer (mechanical isolation).
Lastly, the gametes die before uniting or fail to unite (gamete isolation).
What are some Postzygotic reproductive barriers that differentiate species in the biological species concept?
Hybrid zygotes fail to develop or reach sexual maturity (hybrid inviability).
The hybrids fail to produce functional gametes (hybrid sterility).
Or hybrids are weak or infertile (hybrid breakdown)
Give some examples of prezygotic reproductive barriers.
Habitat isolation: some garter snakes in NA live in water and some on land; Bufo americanus (shallow rain pools) and B. woodhousei (streams) frogs
Temporal isolation: field crickets mature at different times (spring or fall); Eastern spotted skunk mate in spring/summer and western spotted skunk mate in the fall.
Behavioural isolation: Eastern/Western meadowlarks have different mating songs; bluefooted boobys and redfooted boobys are not attracted tp eachother; Galapagos island finches have different songs; frogs mating calls also vary
Mechanical isolation: sympatric monkey flowers– Mimulus cardinalis visted by hummingbirds and M. lewisii are visited by bumblebees
Gamete isolation: Strongylocentrotus purpuratus & S. franciscanus– gametes of red and purple sea urchins are unable to fuse once released into water
What does it mean when two species are sympatric or allopratic?
Two species are sympatric if they coexist in the same area or zone of sympatry.
Species are allopratic if there is no overlap in their habitats.
Give some examples of postzygotic reproductive barriers.
Hybrid inviability: sheep and goat hybrid embryos die due to 54 chromosomes x 60 chromosomes.
Hybrid sterility: Donkey horse hybrids (mule) are sterile
Hybrid breakdown: strains of cultivated rice
What are the rules of binomial nomenclature?
(1) each type of organism has only one name
(2) no two kinds of organisms bear the same name
What are the two parts of the Binomen or name?
(1) generic or genus name (capitalized)
(2) specific epithet (trivial name)
Binomens are italicized or underlined
Describe what happens in the case a scientific name is changed.
Hint: authority, synonym
If the name is changed, the authority remains the same but is put into brackets.
The old name becomes a synonym.
What happens if the same animal is described twice?
The first name is valid and the second name becomes the “junior synonym”
Describe holotype, allotype, and paratype
Holotype: single specimen designated as the name-bearing type of the species
Allotype: specimen of the opposite sex to the holotype
Paratype: specimens of the same species as the holotype that is a part of the species series or record
Who claimed the theory of fixity of species and what influence did Sir John Herschel and Aristotle have?
Plato (falsely) determined that species remain unchanged.
Aristotle believed these fixed life-forms could be organized latterally by complexity.
Sir John Herschel believed God created all creatures and all modern organisms were the unchanged descendants of those organisms
In the late 1700s, which European naturalists suggested that life-forms were not fixed?
George-Louis Leclerc (Comte de Buffon) 1707-1788
Erasmus Darwin 1731-1829
Jean-Baptiste Lamarck 1744-1829
What was Georges Louis Leclerc [Comte de Buffon]’s influence on the transition of ideas around the fixity of species?
He suggested that living things change through time due to migration, geographical isolation, overcrowding, and the struggle for existence (competition).
What was Erasmus Darwin’s influence on the transition of ideas around the fixity of species?
He was aware that modern species were different from their fossils and believed evolution occurred. He also connected the evidence of selective breeding to the change of a species over time.
What was Baron Georges Cuvier’s influence on the transition of ideas around the fixity of species?
Noted that if no species had ever gone extinct due to perfect creation, there should be no fossils found of non-modern species.
Proposed species were destroyed in multiple catastrophes and that different layers contained a different time period before the catastrophe.
Could not explain the new species emerging afterwards, suggested successive creations
What was Jean Baptiste Lamarck’s influence on the transition of ideas around the fixity of species?
Found that fossils show the succession of evolution, from simple morphological forms to more complex forms.
He discovered new species appeared gradually; all species have changed, but rates of change vary; species do not reappear after they have become extinct
Describe Lamarck’s theory of “inheritance of acquired characteristics”
Note: Lamarck was incorrect at the time but agreed with Darwin years later
He believed that organisms acquired the trait when it was advantageous in nature, then those traits were passed to the offspring.
Ex) Giraffes possessed longer necks when the need to eat the leaves higher emerged, then these traits were passed on and the necks grew longer over time
Charles Darwin purposed that over _______’s of million years, species arose from pre-existing species by the process of “____ with _____”.
1000; descent with modification
Summarize Charles Darwin’s early life.
1/5 children of Robert Darwin and Susannah Wedgewood; grandfather was Erasmus Darwin; comes from a long line of physicians.
Abandoned Edinburgh University of Medicine; Bachelor of Arts in Theology from Christ College Cambridge but was more interested in geology & nature courses. Highly influenced by Revd. John Henslow (Prof. Botany) and Adam Sedgwick (Prof. Geology)
How did Charles Darwin end up voyaging on the H.M.S. Beagle?
Revd. George Peacock received a letter from Captain Robert FitzRoy looking for a gentlemen’s companion. He then gave the letter to Revd. Henslow who recommended Darwin
How did Darwin become the ships’ naturalist?
In April 1832 at Rio de Jeneiro the naturalist quit the Beagle.
Darwin became the ships naturalist and his responsibilities included: recording the weather, geological features, plants, animals, fossils, rock and minerals, and Indigenous peoples
