Question

a. Not all evolution is adaptive. Chance plays a role in evolution. Genetic drift can mean certain alleles increase in frequency even when they have negative fitness consequences (remember your population modeling simulations).

b. Selection varies over space. A trait may be adaptive in some other area but not in the area the organism or population currently resides.

c. Selection varies over time. A trait that might have been adaptive in the past may no longer be adaptive.

d. Physical constraints exist. Organisms “bump into” the physical realities of the world.

e. Traits are correlated. Remember this may happen for a variety of reasons. First, they may be on the same chromosome (linked) so if one is selected for the other hitchhikes along. The protein that a gene encodes or makes may have multiple functions (classic pleiotropy) or the traits may simply have a common developmental connection like arm length and digit length.

f. Historical constraints exist. Evolution does not scrap ancestral anatomy and build each new complex structure from scratch but co-opts existing structures and adapts them to new situations. Traits arise through complex evolutionary histories (not a design process). Future evolution is often constrained by traits that have already evolved. Natural selection can only “edit” variation that exists-new alleles do not arise on demand.

g. Adaptations are trade-offs. Each organism must do many different things. Changing one feature for the better might change another for the worse.

h. Evolution is without morality. Just because a trait or behavior has been selected for by natural selection does not mean it is GOOD.

i. Evolution is not progressive. Populations become better adapted to their local environment.

Which letter above goes with which number below? Basically match the letter (Short bolded statements above with their definitions) with a description below this question. Some can be used more than once.

19. ___________________Although forelimbs originally evolved for locomotion on land, birds have modified their forelimbs to fly.

20. ___________________Immune system maintenance and upregulation (“turning on”) is costly. Sexual selection, which increases male investment into reproductive traits, is expected to reduce immune function (McNamara et al 2013).

21. ___________________Scientists have hypothesized that the large, hard-shelled fruit of the calabash tree (a native of Central and South America and the Caribbean) was actually an adaptation for seed distribution by large mammals, such as the gomphothere. Unfortunately, gomphotheres went extinct over 10,000 years ago.

22. ___________________In a traffic jam your heart races and pounds and you get really angry.

23. ___________________A creature the size of a blue whale would not evolve on land because known biological materials could not provide enough support.

24. ___________________As selection increased the frequency of individuals with deeper beaks it also increased the frequency of individuals with wider beaks.

25. ___________________ When semi-aquatic animals such as muskrats and mink swim they use 2.5 to 5 times more energy than fully aquatic mammals such as dolphins and whales.

26. ___________________On a remote atoll in the Pacific a typhoon hit in 1775 reducing the human population from 20,000 to 20. At least 1 of the 20 carried a loss of function allele that when homozygous resulted in a loss of vision. That allele still persists on the island today at frequencies higher than any other population in the Pacific.

27. ___________________Polar bears are probably well adapted to Arctic but they would be a flop in the desert.

28. ___________________Human back problems are often blamed on the fact that we evolved from a tetrapod ancestor so the attachment points for muscles are not necessarily in locations that make the most sense.

Answer 1

19. (c) selection varies over time. When food in land got a lots of competition, birds evolved to find foods high up.

20. (g) Adaptations are trade-offs. Sexual selection, which increases male investment into reproductive traits, is expected to reduce immune function.

21. (i)Evolution is not progress.An adaptation for seed distribution by large mammals was an adaption to continue their existence but not for progress.

22. (h) Evolution is without morality. Just because a trait or behavior has been selected for by natural selection does not mean it is GOOD._In a traffic jam your heart races and pounds and you get really angry. This behavior is called Road Rage. It might have helped the ancestors to express their power when in crowd or to use rage and aggression to help them fulfill their job to survive, but with evolution, we see that this is against morality.

23. (d)Physical constraints exist. Physical and energetic constraints on maximum body size are common. Because marine ecosystems are more productive, and thus provide greater amounts of energy-rich food for consumers, terrestrial environments are considered limiting by comparison, and thus could limit maximum body size.

24. (g) Adaptations are trade-offs. And (e)Traits are correlated. The parallel increase the frequency of individuals with deeper beaks it also increased the frequency of individuals with wider beaks shows that Changing one feature for the better might change another. And may be the chromosome responsible for increase in length and width are linked, that gave the parallel evolution.

25. (i)Evolution is not progressive.When semi-aquatic animals such as muskrats and mink swim they use 2.5 to 5 times more energy than fully aquatic mammals such as dolphins and whales... This is again the adaption for survival, not for progress. Populations become better adapted to their local environment.

26. (a)Not all evolution is adaptive. Chance plays a role in evolution. Genetic drift can mean certain alleles increase in frequency even when they have negative fitness consequences. Here it was by chance that the person with the allel of vision defect survived and passed his gene to his followers.

27 (b). Selection varies over space. A trait may be adaptive in some other area but not in the area the organism or population currently resides. This explains Polar bears are probably well adapted to Arctic but they would be a flop in the desert.

28. (f) Historical constraints exist. Evolution does not scrap ancestral anatomy and build each new complex structure from scratch but co-opts existing structures and adapts them to new situations. Traits arise through complex evolutionary histories (not a design process). Future evolution is often constrained by traits that have already evolved. Natural selection can only “edit” variation that exists-new alleles do not arise on demand. This completely explain why  Human back problems are often blamed on the fact that we evolved from a tetrapod ancestor so the attachment points for muscles are not necessarily in locations that make the most sense.