ANTHRO 2B Module 6 Study Guide:

Macroevolution

evolutionary processes happening above the level of the species; we get new species, genre, family

Microevolution

evolutionary processes happening below the level of species; changes in allele frequencies over time; natural selection, gene drift, gene flow, mutation

Taxonomy

taxa are categories arranged in hierarchical order where the higher order categories are more exclusive (e.g., vertebrates: mammals: primates: etc.); "X is a kind of Y"

Major Categories of Linnaeus Taxa

Kingdom

Phylum (plural: phyla)

Class

Order

Family

Genus (plural: genera)

Species

Binomial nomenclature

genus name + species name

What does "relatedness" mean in an evolutionary sense?

When we say a wolf and a grizzly bear are more related than a horse; what that really means is wolves and grizzly bears have a more recent common ancestry than do with the horse.

Biological Species

-a group of naturally interbreeding populations that reproductively are isolated from other such populations

-Members of the same species can effectively reproduce healthy, fertile offspring

Speciation

when an evolutionary line splits (or branches off) from a common ancestry; a macroevolutionary process whereby the populations of one species splits into two species; this process always involves reproductive isolating mechanisms

Reproductive Isolating Mechanisms

something that divides populations so they are no longer interbreeding; these populations now have the opportunity to become genetically distinct from one another through macroevolutionary processes

Process of Speciation

evident when populations can no longer interbreed

Extrinsic Reproductive Isolating Mechanisms

any factors that produce geographic isolation between populations (e.g., movement of tectonic plates)

Physical barrier in the way of allowing interbreeding populations

Continental drift

movement of tectonic plates

India pushing north onto Asia

Mount Everest increases in height every year

Intrinsic Reproductive Isolating Mechanisms

any isolating technique that does not involve a geographical barrier

Zygote

one-celled organism, fertilized egg

Pre-zygote

prevents the zygote from being formed; prevents the sperm and egg from meeting

Post-zygote

a sperm and egg do not meet, but the zygote undergoes developmental problems

As a result, different genetic instructions might result in spontaneous abortion or sterile offspring

Fundamental Principle of Natural Selection

rate of change is directly proportional to the degree of variability within a population (i.e., populations with high variability are more likely to change)

Corollary

the fate of all evolutionary lineage is extinction

99% of all living beings are gone without leaving ancestral lines

Anagenesis

incremental changes every generation

-From generation to generation, changes are imperceptible

-Ancestors would not be able to breed with original species

Cladogenesis

-speciation proper term

-Populations of a species split into two

Phyletic Gradualism

slow and gradual process of evolutionary change over long periods of time

Emphasizes anagenetic change

Darwin was a proponent of this

Punctuated Equilibrium

long periods of status punctuated by short periods of rapid change

-For most of the time, things do not change much at all but then something happens that triggers a massive burst of change

-Emphasizes cladogenetic change— most change during speciation events

Adaptive radiation

rapid expansion and diversification of a group of organisms as they adapt to newly available ecological space

-A series of cladogenic events, rapid speciation

Generalized

a generalized creature is able to exploit a wide range of ecological space (a broadly defined eco-niche)

- Able to live in a lot of environments but no so well developed to any singular one

- Greater adaptive potential than specialized features

Specialized

a specialize create is able to exploit a specialized environment in a narrowly defined eco-niche

- Able to fit into one environment very well

- Less adaptive potential

Overspecialization

too well adapted to a particular eco-niche

- Leads to extinction

Who is related to whom and how closely?

Relatedness" means recent common ancestor

Anatomical Similarity

a form of evidence that enables us to find common ancestry; two creatures that look more similar to each other have a more recent common ancestor. The more similar species are, the closer ancestor they have

Homology vs. Analogy

use only homologous similarities, not analogous similarities

Homology

similarities between organisms due to common ancestry; two creatures share certain a trait that their last common ancestor also had

Analogy (Homoplasy)

-similarities between organisms that were independently evolved; does not point to a phylogenetic relationship.

-If the common ancestor does not have the same structure as the two species being compared then it is an analogy.

Independent Evolution

-Similar function; similar "solution" to similar selective pressures

-Anatomical similarity due to similarity in function, not common ancestry

-Wings in birds and in insects: same function, not because of common ancestry. Two lines worked independently to get similar structure

Convergence

-Analogy in drastically unrelated organisms; different orders

-Eye of squid, eye of human: photoreceptors in the eye developed independently. Common ancestors did not have the same structure. Evolved on two different evolutionary lines

-Marsupials in Australia & placental mammals (e.g., Tasmanian tiger + dog— dog has more recent common ancestor with a whale)

Parallelism

-Analogy in closely related organisms (recent common ancestor); same taxonomic order

-PRocumbent incisors (bottom teeth just straight out): lemurs & Goeldi's monkey; last common ancestor did not have procumbent incisors

Derived traits

-modification in the ancestral form

-Ancestral mammals had claws (ancestral condition)

-Claws → Nails

-Claws → Hoof

-5 toes → 2 Toes (Cloven hoof)

Shared Derived Traits

-Cloven hoof of a cow, goat, pig, and deer as they share a common ancestor.

-Don't use Ancestral Traits when making lines within a group!

-Use Homologous Shared Derived Traits

Taxonomy of Humans

Kingdom: Animalia (animals)

Subkingdom: Metazoa (metazoans)

Phylum: Chordata (chordates)

Subphylum: Veterbrata (vertebrates

Class: Mammalia (mammals)

Subclass: Theria (therians)

Infraclass: Eutheria (eutherians)

Order: Primates (primates)