Class 22 - End Flashcards
Adaptation
Inherited characteristic of an organism that enhances their survival and reproduction in specific environments
Directional Selection
Selection occurring when conditions favor those with one extreme of a phenotypic range, shifting a population’s frequency curve for the phenotypic character
Disruptive Selection
Selection occurring when conditions favor those at both extremes of a phenotypic range over those with intermediate phenotypes
Founder Effect
when a small group, isolated from the larger population, establishes a new population whose gene pool differs from the source population
Gene Flow
The transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes
Genetic Drift
Allele frequencies fluctuating from one generation to the next
Gene Pool
All copies of every type of allele at every locus in all members of the population
Hardy-Weinberg Equation
p^2 + 2pq + q^2 = 1
Hardy-Weinberg Equilibrium
When a population isn’t evolving– allele and genotype frequencies remain constant from generation to generation (provided that only Mendelian segregation and recombination of alleles are at work)
Microevolution
Change in allele frequencies in a population over generations. Can be due to natural selection, genetic drift, and gene flow
Non-random Mating
When you pick a mate out of proximity as opposed to a luck of the draw out of the entire population of suitors. Like it wouldn’t be random of me to mate with someone from my immediate location as opposed to someone across the globe.
Relative Fitness
The contribution an individual makes to the gene pool of the next generation RELATIVE to the contributions of others
Stabilizing Selection
Selection acting against both extreme phenotypes and favors intermediate variants
Analogous Structure
When species share features because of convergent evolution
→ shares similar function, NOT ancestry
Artificial Selection
Process of modifying species over many generations by selecting and breeding individuals possessing desired traits
Binomial Nomenclature
Two part format for naming species (genus + species)
Biogeography
Scientific study of the geographic distributions of species
Comparative Anatomy
The study of similarities and differences in the anatomy of different species
Comparative Embryology
Compares and contrasts embryos of different species. It is used to show how all animals are related
Convergent Evolution
The independent evolution of similar features in different lineages
Endosymbiosis
Symbiosis in which one of the symbiotic organisms lives inside the other.
Fossil
Remain or trace of an organism from the past
Homologous Structures
Structures in different species that are similar because of common ancestry. ex: mammalian forelimbs
Radiometric Dating
Method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample
Strata
Layers of rock (singular : stratum)
Can show fossil age (top layer of rock would have younger fossils than the bottom layer)
Systematics
Discipline focused on classifying organisms and determining their evolutionary relationships
Taxonomy
Discipline that names and classifies organisms
Transitional Form
Fossils or organisms that show the intermediate states between an ancestral form and that of its descendants
Vestigial Structure
Remnants of features that served a function in the organism’s ancestors but don’t serve a contemporary function
Ancestral Character State
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Character
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Character State
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Derived Character State
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Homoplasy
Analogous structure that arose independently (convergent evolution)
Lineage
A sequence of species each of which is considered to have evolved from its predecessor.
Linnean (Hierarchical) Classification
Kingdom Phylum Class Order Family Genus Species
Outgroup
Species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the species being studied
→ The species being studied is called the ingroup
Phylogeny
The evolutionary history of species or group of species
Principle of Parsimony
The principle that the simplest explanation that can explain the data is to be preferred. In the analysis of phylogeny, parsimony means that a hypothesis of relationships that requires the smallest number of character changes is most likely to be correct.
Taxonomy
Discipline that names and classifies organisms
Allopatric Separation
Gene flow is interrupted when a population is divided into geographically isolated subpopulations.
Allopatric Separation
Gene flow is interrupted when a population is divided into geographically isolated subpopulations .
Allopolyploid
Fertile polyploid that can’t interbreed with the parent species (essentially, it’s a new species)
Autopolyploid
Individual that has more than two chromosome sets that are all derived from a single species
Biological Species Concept
Defines a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but don’t produce such offspring with members of other such groups
Ecological Species Concept
Defines a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment
Hybrids
Offspring resulting from interspecific mating
Macroevolution
The broad pattern of evolution above the species level
Morphological Species Concept
Distinguishes a species by body shape and other structural features
Phylogenetic Species Concept
Defines a species as the smallest group of individuals that share a common ancestry, forming one branch on the tree of life
Polyploidy
Accident during cell division resulting in extra sets of chromosomes
Postzygotic Reproductive Isolating Mechanism
Prevents hybrid from growing into a viable, fertile adult. Done through:
- reduced hybrid viability
- reduce hybrid fertility
- hybrid breakdown (feeble/sterile offspring)
Prezygotic Reproductive Isolating Mechanism
Blocks fertilization from occurring. Done through:
- impeding members of different species from mating
- preventing an attempted mating from completing successfully
- hindering fertilization if mating is completed
Reproductive Isolation
Existence of biological factors (barriers) that impede members of two species from interbreeding and having offspring
Species
The largest group of organisms in which two individuals are capable of reproducing fertile offspring
Sympatric Model of Speciation
When speciation occurs between sympatric organisms.
Sympatry
When organisms exist in the same geographic area and thus regularly encounter one another.
Autotrophy
Organism capable of self-nourishment by using inorganic materials as a source of nutrients and using photosynthesis or chemosynthesis as a source of energy
Biogeochemical Cycle
Pathway by which a chemical substance moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth
Biome
Major life zones characterized by vegetation type in terrestrial biomes or by the physical environment in aquatic biomes
Climograph
Plot of the annual mean temperature and precipitation in a certain region
Detritivore (Decomposer)
Organisms that nourish themselves by eating detritus (nonliving organic waste)
Ecology
Scientific study of the interactions between organisms and the environment
Ecosystem
Community of organisms in an area and the physical factors with which those organisms interact
Energy Pyramid
Shows how energy is transferred from the lowest trophic structure to the highest trophic structure
Food Chain
The transfer of food energy up the trophic level from its source in autotrophs up to decomposers
Food Web
The interconnected feeding relationships in an ecosystem
Heterotrophy
Organism deriving its nutritional requirements from complex organic substances
Primary Production
The amount of light energy converted to chemical energy by autotrophs during a given time period
Producer
Autotroph synthesizing sugars and organic compounds
Trophic Structure (Level)
Refers to whether an organism is a producer, primary consumer, secondary consumer…
where they are on the food chain
Speciation
The process by which one species splits into two or more species
Age Structure
The relative number of individuals of each age in the population
Carrying Capacity (K)
The maximum population size that a particular environment can sustain
Density-dependent
Death rate that increases with population density or a birth rate that falls with rising density
Density-independent
A birth or death rate that doesn’t change with population density
Exponential Population Growth
Population increase under perfect, unlimited conditions, occurring when r[inst] is less than zero and is constant at each instant in time
→ creates a J curve
dN/dt = r[inst]N
K-selection
density dependent selection
Selection for traits that are sensitive to population density and are favored at high densities.
Life History
The traits that affect an organism’s schedule of reproduction and survival
Life Table
Age-specific summaries of the survival pattern of a population
Logistic Population Growth
The per capita rate of increase approaches zero as the population size nears its carrying capacity
→ sigmoid (S) curve
Per Capita Rate of Increase
▲N / ▲t = B - D
Population
Group of individuals of a single species living in the same general area
Density
The number of individuals per unit area or volume
Dispersion
The pattern of spacing among individuals within the boundaries of the population
r-selection
density independent selection
Selection for traits that maximize reproductive success in uncrowded environment
Sex Ratio
.Ratio of males to females in a population
Survivorship Curve
Plot of the proportion or numbers in a cohort still alive at each age
Gross Production
Total primary production in an ecosystem
Net Primary Population
GPP - Ra
GPP is gross production
Ra is the energy used by primary producers for autotrophic respiration)
Primary Consumer
Herbivores that eat plants and other primary producers
Secondary Consumer
Carnivores that eat herbivores
Tertiary Consumer
Carnivore that eats other carnivores
Amensalism
When the interspecific interaction harms one species but doesn’t help or harm the other
Aposematic (Warning) Coloration
Coloring warning of effective chemical defenses
poison dart frog
Character Displacement
Tendency for characteristics to diverge more in sympatric than allopatric populations of two species
Coevolution
The joint evolution of two interacting species, each in response to selection imposed by the other
Commensalism
When the interspecific interaction benefits one species but neither harms nor helps the other
Community
A group of populations of different species living close enough to interact
Competition
When two species use the same resources and one succeeds in winning the resource, the other loses
Competitive Exclusion Principle
.When slight reproductive advantage eventually leads to the local elimination of the inferior competitor
Cryptic Coloration
Camoflage
Fundamental Niche
Niche that can potentially be occupied by a species
Interspecific Interaction
Interactions with individuals of different species
This includes: competition, predation, herbivory, symbiosis, facilitation
Keystone Species
Species not usually abundant in a community but is necessary for the community or it will fall apart
Mimicry
When one species mimics an unpalatable species in order to prevent predation, or when two unpalatable species look similar.
Mutualism
Interspecific interaction between organisms that benefits both species
Ecological Niche
The sum of a species’ use of the abiotic and biotic resources in its environment
Parasitism
When one organism, the parasite, derives its nourishment from another organism, the host, which is harmed in the process
Predation
Where one species, the predator, kills and eats the other, the prey
Realized Niche
Niche that an organism actually occupies
Smaller than the fundamental niche
Resource Partitioning
The differentiation of niches that enables similar species to coexist in a community
Symbiosis
When two or more species live in direct and intimate contact with one another
Anthropogenic Extinction
Extinctions due to human activity.
Background Extinction
The standard rate of extinction in earth’s geological and biological history before humans became a primary contributor to extinctions
Ecosystem Services
All the processes through which natural ecosystems help sustain human life
Edge Effect
The changes in population or community structures that occur at the boundary of two habitats
Exotic (Introduced) Species
Species that humans accidentally or intentionally move from the species’ native regions to new geographic locations
Habitat Island
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Habitat Fragmentation
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Island Biogeography
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Redundancy
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Species-Area Curve
All other factors being equal, the larger the geographic area of a community, the more species it has
