Bio 130 Exam 1

Characteristics of life

Characteristics of life

Cellular, homeostasis, response to stimuli, movement, stores energy

Requirements of life

• Energy

• Essential nutrients

• Liquid water

• Maintenance & reproduction

• Information storage & transfer

• Populations of individuals

• Capacity to evolve

Abiotic factors

non-living aspects of the physical environment, like temperature, water availability, mineral nutrients

Biotic factors

the interactions and effects of other organisms living in the environment that might compete with, prey on, or form beneficial mutualisms with an organism

Ecological Niche Concept

the full combination of abiotic conditions and biotic factors across which individuals can survive, grow, reproduce, and sustain viable populations in the long term

Niche axis

any continuous abiotic or biotic factor important to a species’ survival (e.g., temperature, food resources, abundance of breeding sites)

Fundamental niche

the full range of abiotic conditions (temperature, water, nutrients, etc.) under which a species is physiologically capable of surviving and reproducing to form a population

Realized niche

The environmental niche space actually occupied by a species in the real world – in the face of negative biotic interactions

Negative biotic interactions

reduce survival & performance of most species, constricting the range of abiotic conditions under which the species can actually survive & reproduce at a rate sufficient to form a self-sustaining population

Red Queen Hypothesis

intense biotic interactions, such as parasitism, mutualism, and predation, drive species to continuously evolve adaptations to maintain relative fitness in an ever-changing environment

ecological arms races

Coevolutionary interactions between species that drive evolutionary change in ecosystems and lead to increased biodiversity

“Empty” niches

empty potential niches that a species has not evolved into yet, usually because they do not exist

Niche “construction”

a niche that comes from a species substantially modifying their environment in order to create the unique niche conditions that can support their populations

Competitive displacement (ecological time)

when the presence of one species narrows the realized niche of another in ecological time; ecological time is relatively quick, as the niche shifts as soon as the competition leaves

Character displacement (evolutionary time)

when competition between species causes niche divergence over evolutionary time; the niche might need a while to expand after competition leaves

Niche “differentiation” or “partitioning” (between similar, competing species)

the process by which competing species use the environment differently in a way that helps them to coexist

Natural selection

the process of how organisms “fit” into their niche; survival of the fittest phenotype

Artificial selection

when humans consciously select for or against particular features in organisms (ex. domestication of dogs and creating different breeds)

Evolution (not equivalent to natural selection)

change in gene frequencies across generations; the change in the inherited traits of a population of organisms through successive generations

Genotype

genetic makeup, genome

Phenotype

outward appearance/characteristics resulting from interaction of genotype and environment

Dominant alleles

alleles that are so “powerful” that only one is required for a trait to present itself; masks recessive alleles

Recessive alleles

the “weaker” allele that requires two for a trait to present

Microevolution

small gradual changes over time

Macroevolution

longer and larger processes that result in the formation of a new species (e.g. horses)

Natural selection — “fitness”

natural selection generates fit for a species, or when individuals vary in traits that affects survival and reproductive success

Heritable traits

traits that can evolve and are passed down genetically from parent to offspring

Heritability

whether or not a trait is heritable, which can be tested by comparing the mean of the trait in the parent to the mean of the offspring

Directional natural selection

occurs when environmental pressures favor one phenotype more than the other causing the allele frequency to continuously shift in one direction

Stabilizing natural selection

a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value

Disruptive natural selection

a mode of natural selection in which extreme values for a trait are favored over intermediate values

Convergent evolution

two or more species each independently evolve to have similar forms or adaptations

Evolutionary traps

when ‘adaptive’ traits or behaviors represent changes favored in past generations and not the present; (ex. male australian jewel beetles being attracted to the glossy surface of a beer bottle, baby sea turtles heading toward streetlights and not the horizon)

Adaptive traits

a characteristic or feature of an organism that enhances its survival or reproductive success in a particular environment

Maladaptive traits

a trait that is (or has become) more harmful than helpful

Darwinian algorithms

set behavioral response encoded in DNA by past natural selection on ancestors triggering automatic and stereotyped response to environmental cues that were important to the survival and fitness of its ancestors

Teleonomy

Apparently future goal-directed activities seen in biotic systems that actually emerge from past natural selection leading to the evolution of “Darwinian algorithms”

Speciation

When a group within a species separates from other members of its species and develops its own unique characteristics i.e. turns into a new species

Anagenesis

evolutionary change within a single lineage over time, meaning no new species and no increase in diversity

Cladogenesis

evolutionary change leading to the splitting of one lineage into two or more new species (aka speciation)

Species

hard to scientifically define, but usually similar individuals who can interbreed

Morphological species concept

a concept that characterizes a species based on its physical features or morphology, and cannot explain why or how a species exists

Biological species concept

defines species as groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups; cannot be applied to fossils, prokaryotes, or organisms that live far apart

Phylogenetic species concept

uses analysis of evolutionary trees to guide demarcation of a species, grouping organisms together by an irrefutable common ancestor

Reproductive isolation & gene flow

implies distinct groups/species can form when there is little or no “gene flow” or sexual reproduction between two populations, gene flow meaning the sharing of genes from one population to the other

Allopatric speciation

speciation triggered by geographic separation and barriers that cut off reproduction and gene flow between populations

Monophyletic groups

(a common ancestor and all its descendants) identified by shared, recently evolved, unique traits that are found only in that group due to common ancestry – i.e., inherited from their common ancestor that first evolved the trait or unique genetic characteristic

Cryptic species

Groups of morphologically indistinguishable but evolutionarily distinct related species