Week 10 ~ Evolution & Speciation

What are examples of evidence of natural selection and evolution?

• comparing DNA sequences

• using the CO1 genes sequences, provides signature for species identification

What are some examples of structures and abilities that demonstrate that organisms faced by similar selection pressures have similar adaptations?

• convergent evolution, where unrelated species develop analogous structures or abilities. Examples include streamlined bodies for fast swimming in dolphins and sharks, camera-type eyes in mammals and octopuses, and similar wing structures in birds and bats

Explain how and why a recent evolutionary relationship results in homologous structures.

• they are inherited from a common ancestor, so they all stem from that relationship

What are vestigal structures?

• Structures derived from a common ancestor, but that have that have no apparent function in some species

• e.g pelvic bond and hind legs in some snakes and whales

Examples of homologous structures?

• the limgs of all tetrapods

• limbs of birds and bats and bones that makes up their limbs

What is divergent evolution?

• means that the function of homologous structures may differ in species

How and why does convergent evolution result in analogous structures

• when unrelated species independently adapt to similar environmental pressures or niches. It occurs because natural selection favors identical, efficient solutions (like wings or fins) for survival, regardless of the species' ancestry

What are analogous structures?

• Analogous structures demonstrate that natural selection can lead to similar adaptations in unrelated lineages when they face similar selection pressures

Examples of analogous structures

• the wings in bats and birds: the ability to fly independent of a common ancestor with wings

Example of convergent evolution

• camouflage in artic fox and ptarmigan bird

Compare biological, morphological, ecological and genetic specie concepts

• Morphological: size, color, patterns, leg length

• Biological: whether they are likely to mate and have fertile offspring: mating calls, color of dewlap

• Ecological: the niche or geographical area that individuals occupy

• Genetic species: comparing DNA sequences

What do you think the strengths and weaknesses are

for morphological?

• Morphological:

  • Pros: Easy to use; works for fossils and asexual organisms.

  • Cons: Subjective; fails with cryptic species (look-alikes).

What do you think the strengths and weaknesses are

for biological?

• Biological:

  • Pros: Clear criteria (interbreeding); fits most animals.

  • Cons: Useless for fossils/asexuals; messy with hybrids.

What do you think the strengths and weaknesses are

for ecological?

• Ecological:

  • Pros: Focuses on niche/adaptation; works for asexuals.

  • Cons: Hard to define niche boundaries; niches can overlap.

What do you think the strengths and weaknesses are

for genetic?

• Genetic:

  • Pros: High precision; reveals cryptic species.

  • Cons: Expensive/technical; "percent difference" cutoff is arbitrary.

What does it mean for individuals in a population to be reproductively isolated?

• unable to breed and produce fertile offspring with members of other groups, preventing gene flow. These mechanisms arise from genetic, behavioral, or physical differences, acting as a critical barrier that separates populations and frequently leads to the formation of new species (speciation

*anole lizards on a mainland are NOT this

The dispersal of TWO mainland species has resulted in 150 endemic (i.e. unique) species on the Caribbean Islands. How did this happen?

• adaptive radiation

What is allopatric speciation?

• allopatric:

  • Speciation due to geographical barriers such as mountains, rivers, roads.

What are the similarities between allopatric and sympatric speciation?

• both evolutionary processes resulting in new species, sharing the necessity for reproductive isolation and the absence of gene flow between diverging groups

• rely on natural selection or genetic drift

What is it called when populations are separated by physical structures?

• vicariance

What are the differences between allopatric and sympatric speciation?

• Allopatric speciation involves new species forming due to geographic isolation (physical barriers), while sympatric speciation occurs within a single population in the same location.

• Allopatric is driven by separated populations accumulating changes, whereas sympatric often results from genetic changes (polyploidy) or behavior (niche differentiation).
  

What is sympatric speciation?

• Reproductive isolation between populations take place even if they live within the same geographic area, due to different habitat preferences and/or resources use, i.e. beach, forest floor, tree canopy etc.

Predict which speciation mechanisms that is most likely given certain conditions and situations.

Predict if speciation is likely to occur given certain situations and circumstances.

What is adaptive radiation?

What may lead to adaptive radiation?

What is polyploidy and why may it lead to speciation?

What is speciation?

What are the similarities and differences between autopolyploidy and allopolyploidy

Explain the difference between prezygotic and postzygotic

barriers.

Describe what a hybrid zone is and explain when each hybrid zone type is likely to occur.

Similarities between gradual speciation and punctuated equilibrium?

Differences between gradual speciation and punctuated equilibrium?

When is each of the above speciation likely to occur?