Bio Exam 4

Biological Evolution

Heritable change in a population across many generations.

Microevolution

Small-scale change in a single gene.

Macroevolution

Large-scale change above the species level.

Evolutionary Medicine

Studying and treating human illness and disease through the study of evolution.

Descent with Modification

Species present today descended from ancestral species.

Natural Selection

The mechanism responsible for change in a species over time.

Fitness

The ability of an organism to pass its genes to the next generation.

Mutation

Heritable change in DNA, can be random, rare, neutral, bad, or good.

Homology

Similarity in structures between different organisms due to common ancestry.

Vestigial Structures

Anatomical features with no apparent function but resemble structures of presumed ancestors.

Gene Flow

Genetic exchange due to migration of fertile individuals or gametes between populations.

Speciation

How species arise, a bridge between microevolution and macroevolution.

Polymorphism

Alternate phenotypes influenced by many genes, complex, and potentially influenced by development in utero.

Artificial Selection

Selective breeding to produce desired traits in organisms.

Embryonic Homologies

Developmental resemblances hint at common ancestry, often involving Hox genes.

evolutionary changes in everyday life

antibiotic-resistant bacteria, drug-resistant bedbugs

Plato’s theory on evolutionary thought

every organism was an example of perfect essence created by god, unchanging

Aristotle's theory on evolutionary thought

scale naturae, imperfect → perfect, no room for movement

uniformitarianism

Principle that states geological processes happening today are the same as those in the past, shaping Earth's surface over long periods of time.

catastrophism

Theory suggesting Earth's geological features are shaped by sudden, violent events rather than gradual processes. Popular before uniformitarianism.

point-substitution

common mutation, one base pair substituted for another

large scale mutations

can occur during meiosis, whole chromosomes can be replaced, can have no effect or a large effect

somatic mutation

not passed on to the next generation, an alternation of DNA that occurs after conception

germline mutations

a gene change that occurs in the cell used in reproduction (egg or sperm), passed on to offspring

adaptation

positive mutation

deleterious mutation

a mutation that can have harmful consequences, such as putting a person at higher risk for cancer

homologous structures

the similarity in structures between different organisms due to common ancestry, ancient structures became modified in different ways

hox genes

a group of genes that play a crucial role in determining the body plan of an organism during development. They control the placement and organization of body parts along the head-to-tail axis.

molecular homologies

similar molecular structure of proteins/DNA

analogous structures

similar structures in organisms without shared ancestry, evolved independently to serve the same purpose, evidence for convergent evolution

biogeography

focuses on the distribution of species, species on ocean islands tend to resemble species of the nearest mainland

fossil record

linkages between extinct and extant species

genetic drift

random events that cause allele frequencies to fluctuate unpredictably from one generation to the next, important in small populations

genetic drift - founder effect

individuals isolated from main population, loss of alleles in “founding/new” population

fixed allele

an allele that is the only variant in a population

genetic drift - bottleneck effect

population goes through a period in which its size decreases

directional selection

favors individuals at one extreme of a phenotypic distribution, individuals of one extreme experience poor reproductive success

disruptive selection (diversifying selection)

favors individuals with extreme phenotypes

stabilizing selection

favors individuals with intermediate phenotypes, average is good but extremes are not, reduction in variation

balancing selection

Natural selection that maintains genetic diversity by favoring heterozygous individuals over homozygotes, preserving multiple alleles in a population.

frequency dependent selection

the fitness of a phenotype depends on how common it is in a population

sexual selection

acts on traits that affect reproductive success, survival doesn’t always mean reproduction → animal must find a mate to pass on genes

polymorphism

alternate phenotypes (left-handedness vs. right-handedness), heritable, potentially influenced by development in utero

biological species concept

a group of individuals that have the potential to interbreed and produce fertile offspring

ring species

gene flow occurs between neighboring populations, but at the ends of the “ring” the populations dont interbreed

prezygotic reproductive barriers

no mating attempted

temporal isolation

not at the right time to mate

habitat isolation

not in the right place or time to mate

behavioral isolation

different mating calls

mechanical isolation

morphological features prevent successful mating

gametic isolation

gametes do not unite

postzygotic barriers

mating and fertilization occur; zygote forms

hybrid inviability

hybrid development impaired

hybrid sterility

hybrid cannot reproduce

hybrid breakdown

1st generation hybrid is fertile, 2nd generation is sterile

allopatric speciation

occurs when a population is divided by a physical barrier, leading to the formation of new species due to genetic isolation.

sympatric speciation

occurs when new species evolve from a single ancestral species in the same geographic area, often due to behavioral or ecological factors.

gradualism

theory that evolution occurs slowly and steadily over long periods of time, with small changes accumulating to create significant transformations.

punctuation equilibirum

periods of little change interrupted by short periods of rapid change

adaptive radiations

evolutionary events where a single ancestor species diversifies into a wide range of descendant species to exploit different ecological niches.

ecology

the branch of biology that deals with the relations of organisms to one another and to their physical surroundings

biotic

living

abiotic

non-living

commensialism

symbiotic relationship where one organism benefits while the other is neither helped nor harmed.

mutalism

symbiotic relationship between different species of organisms in which both species benefit

parasitism

symbiotic relationship between different species of organisms in which one organism is benefited at the expense of the other

predation

symbiotic relationship between different species of organisms in which one species benefits and the other dies

population ecology

dynamics of species populations and how the interact with the environment

intraspecific interactions

interactions between individuals of the same species, rely on the same resources, are influenced by the same environmental factors, are likely to interact and interbreed with each other

density

number of individuals/area, limited by resources (food, water) and limiting agents (disease, predators)

dispersion

population distribution pattern

dispersal

movement of individuals away from the population

clumped dispersion

individuals aggregated in patches, often results from uneven distribution of resources and mating/other social behavior

uniform dispersion

individuals evenly spaced, often results from aggressive interactions and severe competition for resources

why is the tertiary sex ratio skewed?

reproduction-related stresses, dispersal (leaving the nest) increases risk of predation in dispersing sex, intraspecific competition, age structure

survivorship curves - late loss

most deaths occur at limit of biological life span

survivorship curves - constant loss

individuals in all age categories have fairly uniform death rates

survivorship curves - early loss

death is prevalent for younger members

life history traits

traits that affect an organisms schedule of reproduction

how do populations grow?

birth + immigration

how do populations shrink?

death + emigration

exponential growth:

rate of population expansion under ideal conditions occurs when no limits are placed on the rate of growth

population limiting factors:

controls on population size/growth

density-dependent population limiting factors

food, space, disease, predation, territoriality, toxic wastes

density-independent population limiting factors

weather, disease

density-dependent controls

depends on population density, higher density → changes in survivorship

density-independent controls

density is not important, abiotic factors

how do density-dependent and density-independent controls interact?

social animals can resist dangerous weather conditions by collective behavior, the greater the pop. density the better the ability to resist environmental stress of density-independent events

what happens to populations when limits set in?

population sizes can crash or stabilize

carrying capacity (k)

maximum population size

logistic growth model

idealized population growth that is slowed by population limiting factors as population size increases

ecosystem stability

diverse ecosystems tend to be more stable and resilient to disturbances

resource utilization

different species have varying resource requirements and utilization patterns

high species diversity allows for ___ efficient use of resources within an ecosystem

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biological productivity

greater species diversity often leads to increased productivity in ecosystems

resistance to invasive species

diverse ecosystems are often more resistant to invasion by non-native species

pollination and seed dispersal

relies on interactions between species, so high species diversity ensures that these critical interactions are maintained

species richness

total number of species within a community

relative abundance

proportion of species within a community

herbivory

eats plants