Dramatic (often temporary) reduction in population size, usually resulting in genetic drift. - Usually the population is all genetically similar

evolution (39) Flashcards by chifuyu! --

Inheritance of acquired characteristics

Who created it? What is it?

Created by Jean-Baptiste Lamarck

Individuals could pass on characteristics they had acquired during their lives to their offspring

[Also proposed that all species evolve over time and in response to its environment, becoming better adapted in that environment. Also, changes are passed from generation to generation.]

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Catastrophism

Who created it? What is it?

Created by Georges Cuvier

Global catastrophes (like floods) caused the widespread extinction of species

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Uniformitarianism

Who created it? What is it?

Created by Charles Lyell

Geological changes are slow & gradual, and natural laws/processes have not changed over time

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Evolution by Natural Selection

Who created it? What is it?

Created by Charles Darwin

Process in which species change over time to best adapt to their environments

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Darwin’s observations

Similar flora (plants) & fauna (animals) on the Galapagos as on mainland South America
Many distinct species of finches & mockingbirds
Fossilized species were similar to present-day species. Ex. Glyptodon (armadillo) & megatherium (sloths)

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Fossil record

Historical, chronological record of all-known fossils documenting life on Earth and the evidence of past life

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Evidence in fossil record

There are fossils of those no longer living
Shallow layers resemble living species
No fossils of most living species
The deeper layers you get, the more simple the fossils are
Fossils are buried deep within rock formations; also, they are found in unexpected locations. Ex. Sea life fossils found in mountain formations & deserts

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Biogeography

Scientific study of geographic distribution of organisms based on both living species & fossils

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Homologous features

Common origin/structure, but different function

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Analogous features

Common function, but different structure

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Vestigial features

Has homologous structure to another species, but it serves no purpose in this species

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Natural selection

The way in which nature favours the reproductive success of some individuals within a population over others

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Adaption

Characteristic/feature of species that makes it well suited for survival or reproductive success in its environment

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Directional selection

Selection that favours a more extreme variation of a trait

Ex. Longer-billed birds are favoured in long-flower environments

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Stabilizing selection

Selection that favours the average phenotype (favoured by the environment; extreme variations are not favoured)

Ex. Average-length billed birds are favoured

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Disruptive selection

Selection that favours opposite extremes of a trait

Ex. Small & large billed birds favoured where there are small & large flowers, both not well-suited for medium-length billed birds

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Sexual selection

Selection that favours the reproductive success of individuals with certain traits over others

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Genetic drift

Random shifting of genetic makeup of next generation (chance). Can result in an allele becoming very common or disappearing entirely.

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Genetic bottleneck

Dramatic (often temporary) reduction in population size, usually resulting in genetic drift.

Usually the population is all genetically similar

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Founder effect

Genetic drift that happens when a small number of individuals establish a new population

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Speciation

Formation of new species

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Species

All members of a population that can interbreed under natural conditions

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Allopatric speciation

Formation of new species from geographic separation. These species eventually become less and less genetically related as evolution goes on.

Ex. Pacific wrasse and caribbean wrasse cannot interbreed due to a thin strip of land called the Isthmus of Panama dividing the wrasse species 2 million years ago.

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Sympatric speciation

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Formation of new species within the same geographic area. Can occur due to competition for resources or mutations. Disruptive selection can lead to this speciation.

Ex. Hawthorn flies laying eggs on both hawthorns & apples after apple trees were brought over to North America.

Reproductive isolating mechanism

Any behavioural/structural/biochemical trait that prevents individuals of different species from reproducing successfully together

Prezygotic mechanism

Prevents interspecies mating & fertilization (formation of zygotes)

Postzygotic mechanism

Prevents maturation & reproduction in offspring from interspecies reproduction (prevents zygote from becoming a viable & reproducing adult)

Behavioural isolation Pre/Post? Desc.? Ex.?

Prezygotic mechanism Different species use different courtship and other mating cues to find and attract a mate. Ex. Male frogs of different species have unique calls that attract only females of their own species.

Hybrid infertility Pre/Post? Desc.? Ex.?

Postzygotic mechanism Hybrid offspring remain healthy and viable, but are sterile. Ex. Mules are the sterile hybrid offspring of a horse-donkey cross.

Mechanical isolation Pre/Post? Desc.? Ex.?

Prezygotic mechanism Differences in morphological features may make two species incompatible. Male damselflies transfer sperm during an unusual mating flight. The male and female genitalia of each species are uniquely shaped and are physically incompatible with other species.

Zygotic mortality Pre/Post? Desc.? Ex.?

Postzygotic mechanism Mating & fertilization are possible, but genetic differences result in a zygote that is unable to develop properly. Some species of the sheep and goat are able to mate, but the zygote is not viable.

Temporal isolation Pre/Post? Desc.? Ex.?

Prezygotic mechanism Different species breed at different times of the year. Pussy willow produce flowers in the early spring. They are reproductively isolated from plant species that produce flowers at a different time of the year.

Hybrid inviability Pre/Post? Desc.? Ex.?

Postzygotic mechanism A hybrid individual develops but either dies before birth or, if born alive, cannot survive to maturity. When tigers and leopards are crossed, the zygote begins to develop but the pregnancy ends in a miscarriage or stillborn offspring.

Ecological isolation Pre/Post? Desc.? Ex.?

Prezygotic mechanism Very similar species may occupy different habitats within a region. The mountain bluebird lives at high elevations, while the eastern bluebird prefers lower elevations and does not encounter the mountain species.

Gametic isolation Pre/Post? Desc.? Ex.?

Prezygotic mechanism Male gametes may not be able to recognize and fertilize an egg of a different species. Many marine animals including corals, clams, and sea cucumbers release their sperm and eggs into open water. The sperm recognizes eggs of their own species through chemical markers on the surface of the eggs.

Adaptive radiation

When a single species rapidly evolves into many different species, filling formerly empty ecological niches. Ex. Finches

Divergent evolution

Large-scale evolution of a group of organisms into many different species, filling specialized ecological niches. Ex. Rodents in Ontario; deer mouse, flying squirrel, beaver

Convergent evolution

Evolution of similar traits in distantly related species (analogous features). Ex. Cacti in South America & Africa

Co-evolution

Process where one species evolves in response to the evolution of another species. Ex. Hawkmoth & star orchid

What is the name of the theory that states that geological changes are slow and gradual and that natural laws and processes have not changed over time? Which scientist is associated with this theory?

Uniformitarianism; Charles Lyell

What is the name of the theory that states that the pattern of fossils could be accounted for by a series of global disasters that wiped out most species on Earth? Which scientist is associated with this theory?

Catastrophism; Georges Cuvier

Which part of Jean-Baptiste Lamarck's theory does not fit with Charles Darwin's theory of evolution by natural selection?

Jean-Baptiste Lamarck proposed that characteristics acquired during an individual organism's lifetime are passed on to their offspring. (Charles Darwin proposed that the characteristics are already present due to natural variations; if they are adaptive, they will be passed on in greater proportion to the next generation)

During his trip on the HMS Beagle, what observations did Charles Darwin make with regard to biogeography?

Charles Darwin observed that fossil species that were similar to living species had the same geographical pattern of distribution (biogeography), suggesting that the living species had evolved from these fossil species.

Name 2 unique species found on the Galapagos islands & describe what is unique about each of them

Marine iguana - No other aquatic iguana species in the world Flightless cormorant - No other species of cormorant that does not fly

The forelimbs of the human, horse, cat, bat, and whale have very similar bone structure, but they are adapted to carry out very different functions. This is an example of a _____ feature. What inference can be made about these organisms?

Homologous; can infer that they have common evolutionary origin (ex. a common ancestor)

The extra toes on pigs' feet that do not touch the ground are examples of ______ features. What inference can be made about the existence of these features?

Vestigial; can infer that the pigs descended from an ancestral species where the toes were used

The wings of birds & the wings of butterflies are both broad, thin, light, and well adapted to their function of flight. They are examples of ____ features. What inference can be made about the mechanism of evolution of these kinds of features?

Analogous; can infer that a similar function (or environment) can lead to similar characteristics developing in organisms that are distantly related

Cheetahs have very little genetic diversity because their population was reduced to just 7 individuals 10000 years ago. This is an example of the _______ effect.

bottleneck effect

The human population of Iceland was started with a relatively small initial population (primarily of Norwegian, Scottish, and Irish origin) more than 1000 years ago. This is an example of the ___________________ effect.

founder effect

Over many generations, a population of hummingbirds gradually has longer and longer bills (beaks). This is an example of ___________________ selection.

directional

Over many generations, a population of hummingbirds has an even greater percentage of individuals with bills of an average length. This is an example of ___________________ selection.

stabilizing

Over many generations, a population of hummingbirds gradually has longer and longer bills, that allow them to feed on certain flowers that have extremely long nectar tubes. This is an example of what pattern of evolution?

coevolution

What are the 2 most common forms of sexual selection?

female mate selection (females choosing males to mate with) & male-versus-male competition (males competing with each other for territory & access to females for mating).

If a population evolves into separate species while within the same geographic area, it is called ___________________ speciation.

sympatric

The evolution of a single species into many new species, filling a variety of formerly empty ecological niches is called ___________________ or ___________________.

adaptive radiation or divergent evolution

The similar body shapes of sharks and dolphins (even though they are not closely related) is an example of ___________________ evolution.

convergent

Male frogs of different species have unique calls that attract only females of their own species. This is an example of ___________________ isolation, which is a ___________________ reproductive isolating mechanism.

behavioural; prezygotic

Zebroids, the hybrid offspring of matings between horses and zebras, cannot reproduce. This is an example of ___________________ which is a ___________________ reproductive isolating mechanism.

hybrid sterility; postzygotic

evolution (39) Flashcards

(58 cards)