ecology exam 2

biological species concept

species were species if the could mate and produce viable offspring

evolution

change in allele frequencies through time in response to selective pressures

phenotype

the set of observable, measurable characteristics and traits of an organism

genotype

an organism’s complete set of genetic material or the specific combination of alleles (gene variants) it carries at a particular location in its DNA

problem with biological species concept.

It assumes there are sexes and gametes (which is not often true) and ignores asexual reproduction.

convergent evolution

the independent evolution of similar traits or structures in unrelated or distantly related lineages

Allele fixation

the state in which an allele reaches a 100% frequency in a population's gene pool

commonality

individuals of the same species should all be able to contribute to the next generation

speciation

when gene exchange decreases to zero between groups of individuals

genes

sequences of dna that encode

mutations

alteration in the nucleic acid sequence in DNA

gene flow

allows genes or alleles to move across populations

genetic drift

chance loss of alleles and genes due to random events

natural selection

the differential survival and reproduction of individuals due to differences in their observable traits and genetic makeup

directional selection

Favors one extreme trait, shifting the population toward that extreme.

disruptive selection

Favors both extreme traits over intermediate traits.

stabilizing selection

Favors intermediate traits over both extremes.

Allopatric speciation

an evolutionary process where a single population splits into new, distinct species because a physical geographic barrier separates them.

sympatric speciation

the evolution of a new species from a surviving ancestral species while both continue to live in the same geographic area

adaptive evolution

the process where natural selection increases the frequency of advantageous, heritable traits in a population while decreasing harmful ones

plasticity

the ability of a single genotype to produce different physical traits, behaviors, or physiological states in response to environmental changes

morphological species concept / morphology

defines a species as a group of organisms that share distinct physical traits, body shapes, and structural features (morphology), making members of the same species look alike, and members of different species look different

does genetic mutation increase or decrease genetic variation

decreases

does gene flow increase or decrease genetic variation

increases

does natural selection increase or decrease genetic variation

decreases

does genetic drift increase or decrease genetic variation

generally reduces

genetic divergence

the process where separated populations of the same ancestral species accumulate independent genetic changes over time

Loss of Gene Flow in isolated population

When physical or biological barriers stop groups from interbreeding, genetic material is no longer shared between them

Independent Mutations effect on isolated population

Random DNA mutations occur in each group separately and build up over generations

Natural Selection effect on isolated population

Different environments or climates favor different traits in each location, pushing the groups to adapt in unique ways.

Genetic Drift effect on isolated population

Random changes in gene frequency (due to small population sizes or chance events) alter each group's genetic makeup independently

CHEAT SHEET FOR DISCRETE AND CONTINUOUS MODELS

discrete population growth

N_t = N_0λ ^t

when is DISCRETE POPULATION GROWTH appropriate

Discrete time models are appropriate for populations that have discrete reproduction (not us!)

λ (lambda)

Finite rate of increase

λ (lambda) > 1

growing population

λ (lambda) = 1

stable population

λ (lambda) < 1

decreasing population

CONTINUOUS POPULATION GROWTH

N_t = N_0e^rt

r

b-d

e

2.7

density dependance

When a critical resource becomes scarce, individuals that use the resource will reproduce less and have lower probabilities of survival

carrying capacity

the maximum population size supported by rescources in the area is carrying capacity denoted as K

Logistic growth

occurs when a population's per capita growth rate slows down and eventually stops as the population size approaches a maximum limit imposed by limited resources in the environment

exponential growth rate

occurs when a quantity or population increases at a constant percentage rate over equal time intervals. Because the growth rate is proportional to the current size, the absolute increase becomes larger and larger with each passing moment, resulting in an unconstrained, rapid explosion.

classification from largest to smallest

Domain, kingdom, phylum, class, order, family, genus, species

classification pneumonic

dear kakorat please clean our fat gatorade spill

Life history

the sequence of events that determine survival and reproduction from an individual’s birth until its death (the things that make up an organism’s life)

Life history traits

Traits that relate to the timing and occurrence of growth, development, reproduction and death. (e.g., age at maturity, timing of molting)

life history strategies

Strategies by which an organism reproduces and survives

monotonic damping

the population approaches a stable equilibrium without repeatedly crossing it.

damped oscillations

oscillates less and less till equilibrium

Stable limit cycle

oscillates repeatedly with a stable pattern

Chaos

Changes irregularly and is highly sensitive to initial conditions