Evolutionary adaptations: evidence, mechanisms, and critiques

What is the function of the long-tailed weasel’s tail spot

acts as a false head to misdirect predators

What is not necessary for evolution by natural selection?

New mutations

What was the theory proposed by Thomas Malthus

Populations are growing faster than resources that support them, and not all individuals can survive

What is the comparative method in evolutionary biology

Observing two conditions and see which one does better

How did researchers study weasel tail spots

They created model weasels, some with and some without tail spots, and observed where predators attacked

What did Darwin’s synthesis combine

• his observations

• ideas from geology

• concepts like population surplus

• Fossil records and animal breeding studies

What challenges did Darwin face in presenting his ideas

• early resistance from the scientific, religious, and political communities

• mockery and criticism before acceptance in the 1850s

What are the main lines of evidence for evolution

1. vestigial traits

2. fossils

3. homologous traits

4. dna evidence

5. lab and field observations

What are vestigial traits

nonfunctional traits that were once useful

What do fossils provide

shows transitional forms and evolutionary patterns

What do homologous traits provide for evidence for evolution

shared traits due to a common ancestor

What makes a scientific theory “robust”?

• supported by multiple independent lines of evidence

• each line is based on many studies

• if one study fails, the theory isn’t discarded

What are the common critiques of evolution

1. some traits are too complex to have evolved

2. gaps in the fossil record

3. missing evidence for big evolutionary transitions

Why are fossil records incomplete

• fossilization is rare

• organisms need to die in water and be buried quickly

• erosion and discovery challenges lead to gaps

Why did early horses have three toes

To move better in swampy environments

Why did later horses evolved to have one hoof

For efficiency in grasslands

Why did horse teeth change over time

their diet shifted from twigs to grass

What evidence supports whale evolution

• whales evolved from terrestrial mammals

• fossils show semi-aquatic ancestors

• vestigial pelvis suggests lost hind limbs

• ear bones link whales to land mammals

What is cumulative selection in evolution

A process where small, beneficial changes build up over generations, leading to complex adaptations.

What is an example of an evolutionary constraint

The laryngeal nerve in giraffes takes an inefficient path due to ancestral fish anatomy

What is parthenogenesis

reproduction without fertilization, an ovum developing into a new individual without fertilization by a sperm

What do whiptail lizards still engage in even though they don’t have to

pseudocopulation due to ancestral behaviors

How do complex structures evolve

• through stepwise cumulative election

• each step provides an advantage for survival

How did insect flight evolve

• stated with moveable gill plates

• gill plates fluttered and helped in surface skimming

• graduallly evolved into functional wings

What evidence supports insect flight evolution

• amber fossils show intermediate stages

• fossils depict longer gill plates evolving into wings

• surface skimming stoneflies represent a half-flying stage

What is experimental method in biology

Artificially making a control and experimental group to compare by designing an experiment

A critique of evolution is that som traits are too complex to have been evoled, what are 2 counter-arguments to this critique?

• cumulative section

• imperfections in nature

What explains the gaps in transitional forms

• new fossils are rare and still being discovered

• filling in gaps creates new gaps

Is it true or false that evolution moves species towards increasing complexity?

false