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118 Cards in this Set
- Front
- Back
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biology
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the study of life
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primordial soup hypothesis
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oceans were full of life-creating compounds that needed energy/catalysts to create RNA and eventually prokaryotes--> eukaryotes
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The Oxygen Revolution
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2.7 billion years ago
reacted iron in ocean, eventually exploding out into atmosphere doomed many prokaryotic groups |
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Cambrian explosion
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A relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record. This burst of evolutionary change occurred about 535-525 million years ago and saw the emergence of the first large, hard-bodied animals
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phylogenetic tree
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mass extinctions
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large numbers of species become extinct as a result of disruptive global environment changes
changes course of evolution forever takes 5-10 million yrs for diversity of life to recover changes type of organisms in ecosystem |
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Permian
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claimed about 96% of marine animal species and drastically altered life in the ocean
enormous volcanic eruptions |
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Cretaceous
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65.5 million years ago
dinosaurs |
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Plate tectonics
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the theory that the continents are part of great plates of Earth's crust that float on the hot, underlying portion of the mantle. Movements in the mantle cause the continents to move slowly over time
Movement of continents enables passive dispersal of organisms b) Consolidation of continents enables mixing of lineages that evolved allopatrically c) Shifts in the latitudinal distribution of continents means that today’s temperate continents once were at least partially in the tropics |
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Adaptive radiation
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Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities
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Development & Gene Regulation
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genes sufficient to produce complex animals existed millions of years before Cambrian explosion--adaptive evolution played key role in shaping diversity of life
change in regulation of a developmental gene may have fewer harmful side effects than a change to the sequence of the gene MUTATIONS AFFECT REGULATION NOT SEQUENCES |
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Linnaeus
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classification of species--nested system, grouping similar species into increasingly general categories
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Lamarck
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species can change--suggested reasons: use & disease, inheritance of acquired characteristics
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Malthus
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population limits--population potential increases faster than food supplies and other resources
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Lyell
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uniformitarianism--mechanisms of change are constant over time; same geological processes operating today
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Darwin & Wallace
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natural selection & evolution
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Key Observations by Darwin & Wallace
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Adaptions
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inherited characteristics or organisms that enhance their survival and reproductions in specific environments
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Natural Selection
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a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits
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Evolution
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descent with modification--characteristics present in an ancestral organism are altered (by natural selection) in its descendants over time as they face different environmental conditions
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Limits of adaption
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-Natural selection acts only on existing variation
-Selection pressures variation -Selection pressures vary in time and space -All traits are subject to trade-offs -Evolution by natural selection is generally slow -Selection can target variation that is not variable |
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Evolutionary traps
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when an evolved and presumably adaptive trait becomes maladaptive and leads to the extinction of a species
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Artificial Selection
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the selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits
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Direct observations of evolutionary change
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beak length for better feeding
drug-resistant bacteria |
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Fossil Record
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documents how new groups of organisms arose from previously existing ones
biased in favor of species that existed for a long time, were abundant and widespread in certain kinds of environments, had hard shells/skeletons |
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Homology
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similarity in characteristics resulting from a shared ancestry
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microevolution
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change in allele-frequencies in a population over generations
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individual heterozygosity
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having different alleles at a gene locus
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Average heterozygosity
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percentage of loci that are heterozygous across genome in a typical individual
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clines
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a smooth change in allele frequencies along a geographic axis
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mutation
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sequence change that forms a new allele
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gene duplication
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new copies can serve new purposes (e.g. olfaction)
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shuffling alleles: sexual reproduction
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mixes alleles in each generation
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Mechanisms of microevolution
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1. Natural selection
2. Sexual selection 3. Genetic drift 4. Gene flow |
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sexual selection
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enhanced mating success leads to changes in allele frequencies
intrasexual selection vs. mate choice |
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Genetic drift
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change in allele frequencies by chance
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Founder effect
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random shift as a large population becomes a small population
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Population bottleneck
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-size of population is reduced
-surviving population is typically no longer genetically representative of original population -natural disaster or human actions |
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Gene flow
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exchange of alleles among populations by immigration of individuals
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Spatial differences
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Temporal differences
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Hardy-Weinberg principle
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states that frequencies of alleles and genotypes in a population will remain constant from generation to generation provided that only Mendelian segregation and recombination of alleles are at work
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macroevolution
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broad pattern of change above the species level
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Biological species concept
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a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring--but do not produce viable, fertile offspring with members of other such groups
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morphological species concept
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characterizes a species by body type and other structural features
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phylogenetic species concept
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species is the smallest group of individuals that share a common ancestor
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pre-zygotic barriers
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impeding mating or fertilization
mechanical isolation: mating may be attempted but prevented by morphological differences gametic isolation: sperm of one species cannot fertilize egg of other species |
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post-zygotic barriers
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prevent viability or fertility of hybrid
hybrid breakdown: initial hybrids are vigorous and fertile, but subsequent generations are not viable |
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allopatry
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gene flow is interrupted when a population is divided into geographically isolated subpopulations
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sympatry
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speciation that occurs in populations that live in same geographic area
polyploidy: extra sets of chromosomes habitat differences sexual selection by mate choice |
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ecology
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study of interactions between organisms and the environment, and how these interactions determine distribution and abundance of species
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organismal ecology
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how an organism's structure, physiology, and behavior meet environmental challenges
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population ecology
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controls on how many individuals of a species live in area
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communication ecology
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interactions among species within the same area
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ecosystem ecology
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energy flow and chemical cycling among biotic and abiotic components
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landscape ecology
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consequences of the arrangement of ecosystems in a region
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global ecology
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distribution and dynamics of species, energy, and materials throughout the biosphere
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biogeography
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spatial patterns of distribution and abundance of species
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Key questions with biogeography
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History: did if fit past environmental conditions?
Dispersion: Was/Is it able to reach this place? Current fitness; does it fit present environmental conditions such that it can survive/reproduce? |
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Dispersal
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movement of individuals, usually from high-density areas to low-density areas
arises from natural responses to population pressures can also result from human activities |
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Continental drift
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Earth's crust is dynamic in geologic time
Evidence of original "supercontinent" of Pangea in fossils as well as taxa |
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natural differences in dispersal
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species choosing to move
herbivores can move farther plants |
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species invasions
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hitch hiking
new environment may have less predators or no limiting resources |
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Habitat selection
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some organisms do not occupy all of their potential range
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biotic factors limiting current distributions
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negative interactions with other species (predators, herbivores) restrict species ability to survive and reproduce
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abiotic factors limiting current distributions
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chemical factors: pH, salinity, oxygen, nutrients in soil
physical factors: temperature, precipitation, soil structure, moisture climate: long term prevailing weather patterns in an area |
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biomes
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major life zones characterized by vegetation type (terrestrial biomes) or by the physical environment (aquatic biomes)
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population
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a group of individuals of the same species that live in the same area
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density
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number of individuals per unit area or volume
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dispersion
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the pattern of spacing among individuals within the boundaries of the population
random, uniformed, clumped |
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Population dynamics
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population size changes through time
Births depend on population size Deaths are not random survival curves differ among species |
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BIDE conceptual model
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Births and immigration add individuals to the a population
Deaths and emigration remove individuals from a population |
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survivorship curve
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a plot of the proportion or numbers in a cohort still alive at each age
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Limits on population growth
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crowding and resource limitation
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density-independent regulating factors
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a birth rate or death rate that does not change with population density
hurricane comes and kills population |
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density-dependent regulating factors
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a death rate that rises or a birth rate that falls as population density rises
competition for resources, predation, toxic waste, intrinsic factors, territoriality, disease |
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sex ratio
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number of males to number of females
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age structure
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the relative number of individuals of each age in a population
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size structure
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% of individuals in different size groups
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community
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a group of populations of different species living close enough to interact
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interspecific vs. intraspecific interactions
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interspecific--individuals in dif species i.e. competition, predation, herbivory, symbiosis
intraspecific-- same species |
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Predation
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+/- interaction between species in which one species, the predator, kills and eats the other, the pray
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defense strategies
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cryptic coloration-- camouflage
toxic defense chemicals aposematic coloration--warning coloration Batesian mimicry-- a palatable or harmless species mimics an unpalatable or harmful one Mullerian mimicry-- two or more unpalatable species resemble each other |
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Symbiosis
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"living together"
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Parasitism
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(+/-)
lives in or on host rarely lethal but can castrate host |
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Disease
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pathogens
generally microscopic, can be lethal both pathogens and parasites achieve very high density and diversity |
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Commensalism
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(+/0)
not very common, "hitch hiking" usually not obligatory |
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Mutualism
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(+/+)
Both symbionts benefits, relationship can be obligatory |
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competitive exclusion
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when two species compete, the inferior competitor will be eliminated over time in a stable environment
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Resource partitioning
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the division on environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niche of all coexisting species
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Character displacement
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tendency for characteristics to diverge more in sympatric than in allopatric populations of two species
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Dominant species
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high abundance or biomass->strong influence
a species with substantially higher abundance or biomass that other species in a community. Dominant species exert a powerful control over the occurrence and distribution of other species |
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keystone species
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low abundance or biomass, yet strong influence
a species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche |
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ecosystem engineers
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strong influence by changing the physical environment
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Food chain
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simple linear hierarchy of who eats whom
distinct trophic levels |
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Food web
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complex network of all existing food chains
no distinct trophic levels more realistic, accounts for all taxa |
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currencies
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organisms transform energy-->energy flow
organisms process materials-->nutrient cycling |
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autotroph
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"self feeding"
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heterotroph
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"feeding on others"
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photosynthesis
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The conversion of light energy to chemical energy that is stored in sugars or other organic compounds; occurs in plants, algae, and certain prokaryotes
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respiration
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releasing chemical energy to do work
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energy pyramid
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tftyyit
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biomass pyramid
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Global energy patterns
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Limits on energy flow
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autotrophs: water, light, nutrients
heterotrophs: water, food |
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Biogeochemical cycles
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transformation of key chemical elements between biotic and abiotic parts of an ecosystem
key elements: Carbon, Nitrogen, Phosphorus |
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Top-down
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A model of community organization in which predation influences community organization by controlling herbivore numbers, which in turn control plant or phytoplankton numbers, which in turn control nutrient levels; also called the trophic cascade model
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Bottom-up
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A model of community organization in which mineral nutrients influence community organization by controlling plant or phytoplankton numbers, which in turn control herbivore numbers, which in turn control predator numbers
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Perspectives on Priorities
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Biodiversity
Ecosystem services |
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Approaches to conservation: endangered species
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assess remaining geographic range & population size to avoid extinction
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Approaches to conservation: Biodiversity hotspots
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regions with high species richness and high threat levels
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Ecosystem services
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regions with unusually high ecosystem levels, should be prioritized
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Millenium ecosystem assessment
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60% of ecosystem services are degraded
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Key threats
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habitat loss, introduced species, over harvesting, global change
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exponential population growth
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growth of a population in an ideal, unlimited environment, represented by a J-shaped curve when population size is plotted over time
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logistic population growth
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population growth that levels off as population sizes approaches carrying capacity
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K-selection
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selections for traits that are sensitive
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carrying capacity
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symbolized by K, as the maximum population size that a particular environment can sustain
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