Bio Final Flashcards
Adaptation
A trait that contributes to fitness by making an organism better able to survive or reproduce in a given environment
Artificial selection
Selection by HUMANS towards a goal. Been done to plants and animals.
Natrual Selection
Selection by abiotic and biotic environment. There is no goal and affects ALL organisms (even humans)
What the natural selection on quantitative traits
Stabilizing, directional and disruptive.
Stabilizing selection
Favors the average of the trait. Ex: human baby weight.
Directional selection
Favors one extreme for the trait.
Disruptive selection
Favors both extremes for the trait.
Population
A group of indivudals of a single species occuping a given area at the same time
Migration
The movement of indivduals from one population to another
Gene Flow
The movement of genes from one population to another.
How to measure gene flow
Looking at potential dispersal v actual interbreeding, using experimental appraches
Stochastic
Unpreditcable or random evolutionary forces (mutation, recombination and gene drift)
Deterministic
Predictable or non random evolutionary force. (natural selection)
Genetic Drift
Random changes in allele frequency due to random variation in fecundity and motility. MOST IMPORTANT WHEN POPULATIONS ARE SMALL.
Population bottlenecks
A single sharp reduection in abundance, usually followed by rebound. Causes a loss of diversity
Founder Events
Colonization by a few individuals that start a new population. Colonizing group contains only limited diversity compared to the source population.
Phenotypic Differentiation examples
Adaptive (local adaptation), due to genetic drift and phenotypic plasticity.
Phenotypic Plasticity
The ability of a genotype to modify its phenotype in response to change in the environment. Occurs though modification to growth and development and behavior. Very unpredictable.
Reciprocal Transplant studies
Growth of equivalent genotypes in contrasting environments and comparisons of their relative performance.
Local adaptation(ecological speciation)
population of organisms evolves to be more well-suited to its local environment than other members of the same species that live elsewhere
What is a species?
Phenotypic similarity, genetic similartiy also used to identify and define speices.
Taxonomic (or morphological) concepts
Based primarily on distinct measurable differences
Biological concepts
Based on inter-fertility among individuals
What are the highlights of biological species concept.
Focuses on the process, geographic isolation alone is NOT sufficient, must be possible interbreeding in the wild and does not apply well for bacteria, asexual, highly self fertitzing speices.
Allopartic
a population or species that is physically isolated from other similar groups by an extrinsic barrier to dispersal leading to evolution.
Sympatric
two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another but lead to evolution.
What is the difference between pre and pro zygotic barriers?
Pre are before the fertilization wheater it’s finding a mate or the zygote and post is wheater the zygote survives in the womb, how well the adult survives and wheater or not the offspring can reproduce.
Pre-zygotic
Prevent mating or fertilization so no zygote gets formed
Post-zygotic
Barriers prevent proper functioning of zygotes once they are formed.
Intrinsic post-zygotic
Inviability, sterility or abnormal development of hybrids
Extrinsic post-zygotic
Ecological mismatch of hybrid phenotype to environment. Cannot be directly favored by natural selection.
Adaptive radiation
The evolution of ecological and phenotypic diversity within a rapidly multiplying lineage as a result of speciation.
What are the four features commonly identify an adaptive radiation?
Recent common ancestry from a single species, phenotype environment correlation, trait utility and rapid speciation.
What causes adaptive radiation
Ecological opportunity, origin of a key innovation and high rates of speciation characterize the clade.
Hybridization
The exchange of genes between speices as a result of occasional inter species mating.
Polyploidy
An organism, tissue or cell with more than two complete sets of homologus chromosomes.
Allopolyploidy
Arises from duplicated karyotype following hybridzation between speices
Autopolyploid
Arises from duplicated karyotype within a species
What is the evolutionary significance of polyploidy
They are reproductively isolated from diploid parents, they exhibit novel phenotypes, and often show hybrid vigor.
Novel phenotypes
a phenotype that is concerned with the unique visual appearance of an organism as compared with its parents
Taxonomy
The theory and practice of classification and naming
Systematic
The study of biodiversity and the evolutionary relationships among organisms.
Monophyletic group
A single ancestor gave rise to all species in that taxon and no species in any other taxon. Includes that complete set of species derived from a common ancestor.
Paraphyletic group
A taxon whose members are derived from two or more ancestral forms not common to all members. Contains some but not all species derived from a common ancestor.
Ancestral trait
A trait shared with a common ancestor
Derived trait
A trait that differ from the ancestral trait in a lineage.
Homology
Similarity of traits due to shared ancestry
Homoplasy
Similarity of traits as a result of convergent evolution.
Convergent evolution
the process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities.
Key innovations
Origin of a novel trait resulting in adaptive radiation, carriers of the trait can exploit new resources or sets of habitats.
Adaptive radiation
An event in which a lineage rapidly diversifies, with the newly formed lineages evolving different adaptations
When is cooperation adative
High relatedness (genes that lead to helping relatives can spread ) reciprocal altruism ( in cases where organisms repeatedly encounter eachother, mutual cooperation can lead to highest fitness BUT it can breakdown.
Unit of selection
Adaptation to the individual that will increase the fitness of the individual, though wheater or not it is good for the species LONG TERM depends.
Meiotic Drive
If an allele can bias its own transmission then it can spread to higher frequency even while reducing individual fitness.
Fair meiosis
here is a 50/50 chance that each chromosome will be passed to a gamete and therefore to offspring
What is a humans main target of selection?
Because genes are the unit of inheritance ultimeately the target of selection is the gene
How do genomes stay so cooperative?
Many features of induvial organism prevent competition within an individual. This ensures that many genes succeed by enhancing the fitness of an organism.
Mitosis and meiosis
Ensures that alleles dont compete within an induvial and meiosis ensures their is fair representation of alleles fitness effects on an individual.
Devolpment and multicellualrity
Starting from a single cell prevents initial competition
among cell lineages
Uniparental inheritance of organelles
Chloroplasts and mitochondria replicate asexually which Prevents competition within cells of different organelle genomes
Over-replication
When a gene makes way more copies of themselves so they will l be on more genomes which makes it more likely to be in offspring.
Transposition selection balance
Transposition balances natural selection and mutational events, so the element can “survive” as a selfish DNA sequence
