Ecology - Chapter 6

Ecology and evolution are _____ and _____

highly related ; interdependent

Charles Darwin was an _____, though he predated the term

ecologist

What was Darwin called during his time?

A naturalist

What books did Charles Darwin write?

Voyage of the Beagle (1831 to 1836) ; The Origin of Species (1859)

Evolution can be considered on a smaller, shorter time scale (____), as well as on a larger, longer time scale (_____)

microevolution ; macroevolution

Alternative forms of genes

Alleles

The genetic makeup of an organism (its collection of alleles)

Genotype

The physical expression of an organism’s genes (its morphology, anatomy, physiology, and behavior)

Phenotype

The number of offspring produced by an individual, relative to the number of offspring produced by all other individuals in the population

Fitness

Allele frequency changes within a population over time

Microevolution

Mechanisms of microevolution

Mutations, sexual reproduction, genetic drift, gene flow, natural selection

Changes in genes due to changes in the nucleotide sequences of DNA

Mutations

What causes mutations?

Errors during DNA replication and cell division, usually resulting from exposure to chemicals or high-energy radiation

The ultimate source of new alleles within a population

Mutations

What rearranges existing alleles into new combinations by way of crossing over, independent assortment of chromosomes, and random fertilization?

Sexual Reproduction

What is a greater contributor to genetic variation than mutations in sexual organisms?

Sexual Reproduction

Change in the allele frequencies of a small population due to random chance

Genetic drift

Change in the allele frequencies due to immigration into or emigration out of a population

Gene flow

The evolutionary process where organisms with inherited traits that better suit their environment tend to survive and reproduce more successfully than others

Natural Selection

Most variation among individuals within a population is _____

genetically inherited

Overproduction of offspring leads to offspring _____ for resources

competing

Reproductive success is ____

unequal

What changes as certain traits increase while others are eliminated?

Allele Frequencies

Features that improve an organism’s ability to survive and reproduce in its environment

Adaptations

Examples: Hummingbirds, Chameleons

What involves adaptations increasing in frequency within a population over time?

Adaptive evolution

The only mechanism of microevolution that consistently promotes adaptive evolution

Natural selection

Defined by Darwin as “descent with modification” (descended from common ancestor, but modified from that ancestor)

Macroevolution

The process by which an ancestral species gives rise to a descendant species

Speciation

Macroevolution encompasses speciation

Two organisms belong to the same species if they have the potential to ____

mate in the wild and produce viable, fertile offspring

The formation of new species involves the formation of ____

reproductive barriers

Mechanisms of macroevolution

Allopatric speciation ; Sympatric speciation

An evolutionary process where a geographical barrier physically splits a population in two and prevents gene flow between the new populations. Each population undergoes microevolution independent of the other population. If the two populations are brought back together and can no longer interbreed, they have evolved into separate species

Allopatric Speciation

When part of a population becomes reproductively isolated in the midst of its parent population. This is most frequently seen in plants, it happens due to mutations, and there is no geographic barrier

Sympatric Speciation

When natural selection produces similar phenotypes in organisms that are not closely related due to the same environmental selection pressures

Convergent Evolution

When two species exert selective pressures on each other, resulting in both evolving together due to interactions such as mutualism and parasitism

Coevolution

A type of natural selection in which the limited resource for which individuals compete is mates, and the “environment” that selects for advantageous traits is the opposite sex

Sexual Selection

A ____ evolves, not an ______

population ; individual organism

An individual organism can respond to changing conditions by altering its physiological processes

Acclimatization (acclimation)

A population (species) responds to changing conditions by evolving

Adapatation

The interactions between organisms and their environments

Ecology

What is driven by the interactions between organisms and their environments

Evolution