Bio 1407 Exam 1 Blinn Hutchinson

Biogeography

trends in the geographic distribution of species

Catastrophism

species found in one stratum were destroyed by a catastrophe and new species from surrounding areas repopulated

Uniformitarianism

slow, continual forces that caused change long ago are still at work now

Endemic

animals found nowhere else in the world

Adaptations

inherited characteristics of organisms that enhance survival and reproduction in a given environment

Natural Selection

process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits

Artificial Selection

human modification of other species by selecting and breeding individuals with desirable traits

Homology

similarity resulting from common ancestry

Homologous Structures

structures found in related species that represent variations on a structural theme that was present in their common ancestor

Vestigial Structures

remnants of features that served a function in an organism's ancestor but serve little/no purpose in the modern species

Convergent Evolution

independent evolution of similar features in different lineages to deal with the same environmental conditions

Analogous Structures

rather than homologous structures

Continental Drift

All of the continents formed one landmass called Pangea 250 Million Years Before Present (MYBP)

Broke apart ~200 MYBP and began drifting...roughly in current position for last 20 MY

Microevolution

evolutionary change at the smallest level possible, the population level

Genetic Variation

differences among individuals in the composition of their genes or other DNA segments

Heritable

variation that can be passed from one generation to the next

Discrete

either one variant or the other (black/white)

Quantitative

many variants present on a continuum (Black/dark grey/grey/light grey/white)

Average Heterozygosity

average percentage of gene loci that are heterozygous

Genetic Drift

chance events that cause allele frequency to fluctuate unpredictably among generations

Founder Effect

because the new pop. is small, the proportion of alleles is likely to be unbalanced and create rapid evolution

Gene Flow

transfer of alleles into or out of a pop. due to the movement of fertile individuals or their gametes

Immigration

movement into a population

Emmigration

movement out of a population, also includes birth/death in population

Relative Fitness

the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

Directional Selection

environment favors one extreme of a phenotypic range

Disruptive Selection

environment favors both extremes of a phenotypic range

Stabilizing Selection

environment selects against both extremes and favors intermediate phenotypes

Sexual Selection

individuals with certain inherited characteristics are more likely than other individuals to obtain mates

Sexual Dimorphism

difference between two sexes in secondary sexual characteristics

Intrasexual Selection

competition between members of the same sex decides who wins mating chances

Intersexual Selection

aka mate choice; member of one sex selects a mate from the opposite sex

Speciation

process by which one species splits into two or more species

Macroevolution

broad pattern of evolution above the species level

Biological Species Concept

group of pops. whose members have the potential to interbreed in nature and produce viable, fertile offspring- but do not produce viable, fertile offspring with members of other such groups

Prezygotic

barriers that prevent fertilization from occurring between two different species

Postzygotic

barriers that prevent hybrid zygotes from developing/reproducing

Hybrid

offspring resulting from mating between two different species

Morphological Species Concept

species are identified by body shape and other structural features

Ecological Species Concept

species identified by the niche, the sum of all interactions a species has with the living and nonliving parts of the environment

Phylogenetic Species Concept

species is smallest group of individuals that share a common ancestor, forming one branch on the tree of life

Allopatric Speciation

population is divided into geographically isolated subpopulations

Sympatric Speciation

speciation occurs in populations that live in the same geographic area (ranges of populations overlap)

Polyploidy

accident during cell division (meiosis) that results in extra sets of chromosomes

Punctuated Equilibrium

dominant pattern in fossil record is long periods of little change and then massive amounts of change in a short period of time

Ribozymes

RNA molecules that can serve enzyme-like catalytic functions

Geological Time Scale

division of Earth's history into ordered, named, periods of time based on major biotic and abiotic changes

Stromatolites

layered rocks formed when prokaryotes bind thin films of sediment together

Eukaryotes

cells with nuclear envelope, mitochondria, endoplasmic reticulum, cytoskeleton

Endosymbiotic Theory

posits that eukaryote arrival corresponded to larger prokaryotic cells engulfing smaller, free-living prokaryotes that became mitochondria and chloroplasts

Cambrian Explosion

period of rapid evolutionary change 535-525 MYBP when several modern phyla appeared and others diversified in the fossil record

Plate Tectonics

theory- continents are part of plates of Earth's crust that essentially float on hot, underlying portion of the mantle

Adaptive Radiation

periods of evolutionary change where groups of organisms form many new species whose adaptations allow them to fill different ecological roles in communities

Phylogeny

evolutionary history of a species or group of species

Taxon

each level of hierarchy referred to as a ____________

Phylogenetic Tree

representation of evolutionary history of a group using a branching diagram

Homoplasies

Similarities from convergence

Fossorial

digging underground adaptation

Molecular Systematics

discipline that uses data from DNA and other molecules to determine evolutionary relationships

Cladistics

approach to molecular systematics in which biologists attempt to place organisms into clades based on common ancestry

Monophyletic

clade consists of an ancestral species and all of its descendants

Paraphyletic

clade consists of an ancestral species and some, but not all, of its descendants

Polyphyletic

clade consists of taxa that have two or more ancestors (not one common ancestor)

Shared Characters

character arose in an ancestral form and all descendants of that ancestor have that character in common

Apomorphies

shared derived characters

Pleisiomorphies

shared ancestral characters

Outgroup

species or group of species from an evolutionary lineage known to have diverged before the lineage of the species we are studying

Ingroup

presumed to share a common ancestor and be more closely related to each other than any one is related to the outgroup species

Evolution

a change in allele frequency over time

Evolutionary Theory

understanding and application of the mechanisms of evolutionary change to biological problems

Gene Pool

all of the alleles of all of the genes existing in all individuals of a populations

Mutation

ultimate driver of all other variation/random change in nucleotide sequence

Species Concept

Species is the smallest group of individuals that share a common ancestor, forming one branch on the tree of life. (?)

Lineage species concept

species is one branch on the tree of life which has a history that starts at a speciation event and ends either at exctinction or at another speciation even

Sister species

species who are each others closest relative

Radiometric dating

method of determining the age of objects such as fossils and rocks based on the decay rates of radioactive isotopes

Half life

time required for half of a sample of a radioactive isotope to decay to its stable, non-radioactive form