Ecology and Evolution Exam 2

What is heredity

Transmission of traits from one generation to the next. Specifically, traits that have a genetic basis.

What is a gene

Unit of heredity info consisting of DNA sequence

What is an allele

An alternative form of a gene that occupies the same position on a chromosome and can result in different traits.

What is a trait

A characteristic of an organism that is either seen or unseen. Can be inherited, shaped by the environment, or a combo

What is DNA

Double-stranded molecule with complementary pairing of building blocks (A-T; C-G), organized into chromosomes

What is the central dogma

Information flow from genotype to phenotype

What is a locus (loci)

Specific location of a gene

What is heterozygous

Having two different allele for a gene

What is homozygous

Having two identical alleles for a gene

What is a chromosome

single long DNA strand coiled around proteins (histones); segments of DNA that contain info to build proteins called genes

What are homologous chromsomes

chromosomes having the same genes at the same loci but possibly different alleles

What are sister chromatids

Identical copies of a chromosome joined together

What are non-sister chromatids

Chromatids from homologous chromosomes

What is meiosis

Sexual cell reproduction. Includes synapsis, crossing over, and the chromosome number being cut in half. Creates 4 non-identical haploid cels.

What is mitosis

Asexual cell reproduction. No synapsis of homologous chromosomes, creates 2 identical diploid cells

What is crossing over

Process where non-sister chromatids of paired homologous chromosomes exchange segments of DNA

What is the law of independent assortment

23 pairs of chromosomes; the way in which pair 1 aligns is different than pair 23. Random independent assortment.

What is gametes

Sperm or egg sex cell that unites with another gamete to reproduce

What does haploid mean

Single set of chromosomes, therefore half the total number of chromosomes, 23.

What does diploid mean

Two complete sets of chromosomes, one from the mother, one from the father. 46 chromosomes arranged in 23 pairs.

What is asexual reproduction

Reproduction from a single parent. Results in genetically identical offspring

What is sexual reproduction

Reproduction from two parents. Results in genetically unique offspring that have combined genes from both parents

What is the cost of meiosis

Halving your genetic contribution to next generation

What is the cost of males

Females without males produce more offspring

What is the Red Queen Hypothesis

come back

What is anisogamy

Unequal-sized gametes, with one usually motile, the other is not. Ex. Most plants and animals

Isogamy

Equal-sized gametes (may be motile or non-motile) Ex. fungi, some algae

What is sexual selection

The component in the process of natural selection that tends to perpetuate the hereditary characteristic that attracts one sex to the other. Or: Allows one sex to compete for access to the other sex, even if those characteristics confer no other survival advantage to the possessor.

What is Trivers’ Parental Investment Theory of Sexual Selection

When one sex invests more time and energy per offspring than the other, the high investment sex cannot reproduce as often as the other. Thus, the high-investing sex is limiting resource for the reproductive potential of other sex

What is intrasexual selection?

Competition within the same sex for access to mating opportunities.

What is intersexual selection?

Differential attraction/selection of mates. One sex might choose a mate based on color, display, etc. (Mate choice)

What is sexual dimorphism

Differences between sexes

What is population genetics

Focuses on populations as the evolutionary units, the smallest unit that can evolve, since individuals can not evolve.

What is genotype frequency

the proportion of individuals in a population with a specific genotype

What is allele frequency

the proportion of a specific gene at a specific locus in a population

What is the Hardy-Weinberg equilibrium

Predicts allele frequencies when the population is not evolving. It assumes: random mating, no mutations, no natural selection, no gene flow, and a large breeding population (P²+2pq+q²=1)

What is gene pool

Specific to population genetics, includes all copies of every allele at every locus in all members of the population

What is negative frequency dependent selection

When the least common trait has a selective advantage (higher fitness)

What is balancing selection

Preserves allele diversity by maintaining a stable allele frequency

What is heterozygote advantage

An individual with two different alleles has a higher fitness than homozygous individuals (malarial parasite)

What is genetic drift

Process in which chance events cause allele frequencies to fluctuate unpredictably from one generation to the next. Random deviation is higher in small populations

What is the bottleneck effect

Occurs when there is a drastic reduction in population size due to a sudden change in the environment, therefore resulting gene pool may be different than the original one

What is founder effect

Occurs when a few individuals become isolated from a larger population. Allele frequencies in the smaller founder population are different from the parent population

What is gene flow (immigration, emigration)

Species are added to the population through immigration, removed through emigration Come back

What is speciation

Formation of new species, bridges processes of microevolution and macroevolution

What is anagenesis

Phyletic evolution, change within a lineage that leads us to consider the descendant species a new species and the ancestral species to not exist. Does not lead to diversification.

What is cladogenesis

Branching evolution, splitting of an ancestral parent species into 2 or more species, leading to diversification

What is the biological species concept

A group of organizations that can successfully interbreed and produce viable, fertile offspring constitutes a new species. Formation of new species hinges on reproductive isolation by pre or post zygotic barriers

What is morphological species concept

Members of a species are phenotypically similar to one another and look different from other sets of organisms.

What is the phylogenetic species concept

A species is the smallest set of organisms that share an ancestor and can be distinguished from other such sets, the tip of a phylogeny (evolutionary tree)

What is allopatric speciation

Gene flow interrupted by a geographic divide

What is sympatric speciation

Gene flow is interrupted despite lack of geographic divide

What is parapatric speciation

A new species evolves from a small, isolated peripheral population

What is vicariance in terms of geographic isolation

Split a species distribution (Ex. River dividing and creating subpopulations)

What is dispersal in terms of geographic isolation

Dispersing from the mainland and ending up in different places causes separation, leading to divergence

What is polyploidy in terms of isolation

Extra sets of chromosomes occur in gametes as a result from accidents during cell division, can lead to new species in single generation without geographic seperation

What is habitat differentiation in terms of isolation

Speciation results from the exploitation of new habitats or resources

What is sexual selection in terms of isolation

Sympatric speciation can be driven by sexual selection

What is a hybrid zone

Regions where members of different species mate and produce hybrid offspring.

What is adaptive radiation

Evolutionary process in which a lineage shows rapid diversification/speciation in response to an open ecological niche.

What is a prezygotic reproductive barrier

Habitat isolation, temoporal isolation (mating at different times of the year), behavioral isolation (courtship rituals - don’t recognize eachothers calls), mechanical isolation (different reproductive parts, mating won’t work), gametic isolation (Gametes won’t fuse)

What is a post zygotic reproductive barrier

Reduced hybrid viability (less likely to survive hybrid), reduced hybrid fertility (hybrid is infertile), hybrid breakdown (over multiple generations, feritlity is lost)