BIOLOGY 2 (Exam #1)

Microevolution

Change in allele frequency over time, obsevable and measurable

Gene Pool

All of the alleles for all genes in a population

Chromatin

Mixed up snarled up DNA in nucleus, DNA linear

Condensation

DNA changes shape when doing mitosis or meiosis

Chromatids

2 100% genetically identical strands of DNA

Homologous chromosomes

Same genes but not necessarily same alleles

p² + 2pq + q²

Hardy Weinberg Equation

p²

Frequency of HH

2pq

Frequency of Hh

q²

Frequency of hh

p

Frequency of dominant allele (H)

q

Frequency of recessive allele (h)

Very large population, no immigration or emmigration, random mating only, all offspring are likely to survive and reproduce, no mutations

5 Conditions of HWE

Population shows genetic variation and allele frequency change

Requirements for Natural Selection

Fitness

Measurement of offspring ability to reproduce (grandchildren count)

Directional, Disruptive, Stabilizing

Three patterns of Natural Selection

Directional

Curve shifts

Disruptive

Extremes are high

Stabilizing

Intermediate is really high

Intrasexual selection

Direct competition among individuals of one sex (often males) for mates of the opposite sex

Intersexual selection

Where members of one sex choose mates from the opposite sex based on specific traits

Balancing selection

Preserves variation at some loci by maintaining stable frequencies of two or more phenotypes

Frequency-dependent selection

Fitness of phenotype depends on how common it is

Genetic Drift

Chance events cause allele frequencies to fluctuate unpredictably from one generation to the next

Founder effect and Bottleneck Effect

Two types of Genetic Drift

Founder effect

When a few individuals become isolated from a larger population and starts a new population

Bottleneck Effect

Drastic reduction in population size due to a sudden change in the environment (natural disaster)

True

T/F: Genetic drift is signiciant in small populations and can cause allele frequencies to change at random

Gene Flow

Movement of alleles among populations (ex: pollen and the wind)

Aristole

Which philospher believed species were fixed (unchanging)?

Scala Natura

What scale of complexity did Aristotle arrange species on?

Gradualism

Hutton and Lyell both helped propose this principle

Malthus

Who published “Essay on Principle at Population”?

Lamarck

Who proposed the hypothesis that physical changes acquired by an organism during its lifetime can be passed on to its offspring? (ex: giraffe)

Adaptations

Inherited characteristics that enhance organism’s survival and reproduction in specific environments

Natural selection

Individuals with certain inherited traits tend to survive and reproduce at higher rates because of those traits

Charles Darwin

HMS Beagle, Wrote “The Origin of Species”, natural selection theory

Descent with Modification

All organisms are related by descent from a common ancestor that lived in the past

Direct observations, Homology, Fossil Record, Biogeography

4 Types of Data that document pattern of evolution

Homology

Similarity resulting from common ancestry

Homologous structures

Body parts in different species that have a similar underlying anatomical design but serve different functions (common ancestor present)

Comparative embryology

Reveals anatomical homologies not visible in adult organisms

Vestigial structures

Remnants of features that served a function in the organism’s ancestor

Analogous structures

Not same evolution origin, not controlled by the same genes but they do have the same function (ex: butterfly wings and bat wings)

Molecular Homologies

Includes genetic code shared by all life and specific genes that are shared between vastly different organisms

Biogeography

The scientific study of geographic distribution of species provides support for evolution (ex: continental drift)

Rare, Incomplete, Biased towards organisms w/ hard parts

Limitations of Fossil Record

Macroevolution

Large-scale evolutionary changes over long periods

Speciation

The evolutionary process where one species splits into two or more distinct and separate species

Genetic Variation

The "raw material" of evolution

True

T/F: If observed genotype frequencies match expected values calculated from Hardy-Weinberg equations, the population is in equilibrium. If observed is not equal expected, evolutionary forces (or non-random mating) are acting on the population.

Artificial Selection

Selection directed by humans

Biological Species Concept

Defines a species as groups of interbreeding natural populations that produce viable, fertile offspring

Morphological Species Concept (MSC)

Defines species based on physical structure/appearance

Ecological Species Concept (ESC)

Defines species based on their ecological niche/role in the environment.

Phylogenetic Species Concept (PSC)

Defines species based on the smallest group of individuals sharing a common ancestor (evolutionary lineage)

Prezygotic Barriers

Barriers prevent fertilization/mating from occurring

Temporal Isolation, Behavioral Isolation, Habitat Isolation, Mechanical Isolation, Gametic Isolation

Types of prezygotic isolation

Temporal Isolation

Isolation where species reproduce at different times

Behavioral Isolation

Isolation where mating behaviors/signals are different

Habitat Isolation

Isolation where species live in different habitats, so they rarely encounter each other

Mechanical Isolation

Isolation where reproductive structures don't fit/work together

Gametic Isolation

Isolation where sperm and egg cannot fuse

Postzygotic Barriers

Barriers that reduce survival or fertility after a hybrid zygote forms

Reduced Hybrid Viability, Hybrid Sterility, Hybrid Breakdown

Types of postzygotic barriers

Reduced Hybrid Viability

Hybrids fail to develop

Hybrid Sterility

Hybrids survive but are infertile (ex: mule)

Hybrid Breakdown

First generation is fertile, but next generation is sterile/weak

Allopatric Speciation

Speciation driven by georgraphic isolation (ex: a river or canyon physically dividinga population)

Sympatric Speciation

Speciation occuring without geopgraphic isolation (ex: polyploidy, sexual selection, or habitat differentiation)

Polyploidy

An error in cell division resulting in extra sets of chromosomes, common in plants

Reinforcement, Fusion, Stability

Hybrid Zones Outcomes

Reinforcement

Hybrids are less fit; reproductive barriers strengthen over time

Fusion

Reproductive barriers weaken; the two species merge back into one; Hybrids have high fitness

Stability

Hybrid Zone persists

Mendel

Who demonstrated particulate inheritance (genes act as discrete units)?