Divergence
-mechanisms that increase divergence: mutation, genetic drift, non-random mating, selection
-counteract, decrease divergence -migration (gene flow), keeps populations from diverging
Speciation
-process of population diverging leading to distinct species
↳ one big population -> > 2 population -> -> distinct species (evolutionary images = divergence over time -> identification of things different from one another
-1. 2 million described species = many undiscovered (7-15 million)
How to identify species
-both agree: independent evolutionary units + units should lack gene flow > ways to delimit biodiversity of species
-disagree: Criteria not good, mask evolutionary history + biodiversity
-biologic species concept (BSP)-reproductive isolation, no interbreeding + hybrids are sterile struggle with hybridization
↳ counter orange + black birds -different species, one in east-west, but overlap
-hybridize with one another a still able to reproduce = exchange genes, not reproductive isolated = 1 species
-evolutionary history-shared characteristics = branching events, two birds are not sister taxa-not most closely related: different evolutions
guessing -hard to judge whether something is able to reproduce with each other
-phylogenetic species concept - the smallest diagnosable monophyletic group one GOO
↳ assess similarities + differences among the features of organisms -> shared ancestry = monophyletic group -> species
↳ ex. identify birds as 2 species, conflict BSC does not consider gene flow /not care hybridization
↳ characteristics diverged to identify two things differently, shared derived character emerge in one different from another)allows hybridization
-process of lineage diverging
-some individuals isolated from others /no gene exchange)-not gene flow cause diverge, characteristic diverge only in one population = 2 species
↳ sometimes gene flow between two=not Isolated -> more emerge -not reproductive
-differ in when they can identify species (PSC = sooner
-struggles of biological species concept -> hybridization
↳ asexual reproduction (exbacterial -no exchange genes ↳ plants hybridize c lot
-PSC ability to discover /species --influence conservation impacts (ex. accidentally wiped one out
↳ ex. Asian African Elephants -> (African Safari different morphology from forest)
-African-forest + safari -> > infer evolutionary history, forest more closely ancestry than safari = 2 African species
Speciation
-2 steps:
-divergence (mutation, selection, non-random mating, genetic drift)
-interrupt gene flow/migration
↳ physical isolation = allopatric model of speciation -physical barrier to gene flow
-dispersal-barrier is space, (barrier in habitat, ex water mainland to island
-vicariance -"splitting," barrier insert among individuals, usually slower, ex. Mountain range rising, continental drift
ex. glaciers -forces forest to separate, reproduction isolation, glacier melts -> forest returns with more species -> hypothesize sister taxa
↳ Hawaiian islands -plate tectonics move, islands form, dispersal to new islands (dispersal -+> divergence -> speciation)
-the oldest island is most distantly related
-endemic-native/isolated to certain area
↳ without physical separation = sympatric model-strong selection can lead to functional barrietta
↳ ex. 830 species in the lake not due to isolation
↳ strong selection/preference for specifics adaptive radiation -burst of speciation
-secondary conduct -come back into contact
↳ no reproduction-reinforce speciation: 1. Ignore each other 2. physically cannot mate
-gametric isolation, behavioral isolation, temporal isolation, habitat isolation
↳ reproduce-mate, have hybrids
-if hybrids have lower fitness -> selected against, die out, = speciation reinforced, reproductive isolation
-hybrids equal fitness-reestablish gene flow, may erase speciation
-speciation = divergence of population continually over time
-selection drives speciation (can be rapid)
-evolution has no goal, not trying to create something; results of divergence + speciation
-speciation creates biodiversity, patterns of landscapes = ecology
Ecology
-study of species, interactions with each other + environment
-sets up how evolution unfolds
-niche-role a species has in environments
- abiotic-water, temperature, sunlight, soil, kind -limitations exist for species to tolerate
- biotic -food source, predators, competition
Ecological Niche
-facet where species exist, live a refine where species live
-composed of biotic + abiotic factors
↳ abiotic -physical, nonliving things, represent the aspect of species existence (soil, sunlight, water, temperature
-limited by/present challenges -> how evolution shapes niches
-add together -> makes climate-dictates what ecosystem/biome lives there
-ecosystem/biome-collection of species that live there, such as a climate
↳ pattern to where ecosystems exist (ex. Equator vs. pole)
-sunlight-ultimate driving source, why ecosystems exist where they do (tilt-seasonal, more energy /sun = more diversity
-define ecological niche of species => measure the range of abiotic factors that the species can exist
↳ map of where the species can exist
↳ data can lead to rules needed by species
-identify the current niche of species + other available nice space of species -> define parameters that make up an abiotic niche
-speciation = different niches, Selection for niches = speciation
-principle hypothesis of niches
↳ competitive exclusion hypothesis -two species cannot occupy the same niche in exact same location
- partition resources in sympathy (among each other)-ex· different species of bird forge different parts of free /divide up
-character displacement -not direct competition, ex. Length of bills = access different resources in water, hypothesize past selection
-why don't species occupy all possible niche
↳ barrier, not able to access/occupy area ↳ species never exist there ↳ disease/parasite interactions
↳ another species already occupies ↳ other species (even humans)remove it
-species niches can expand (ex. wolves)-> niche space that is available
-biotic features -> interactions with other species = communities
-community - a collection of species that live together in an ecosystem or habitat
↳ trends in community diversity: tropics are the most diverse (most interactions with other species) + high mountain area
-more sunlight/solar energy + older ecosystem (no glaciers)
-area increase = biodiversity increase
↳ island equilibrium model: more likely to receive emigrating species, lose species (extinction)slower
-if two islands closest to the mainland are more diverse
~ humans shrink habitat size; bigger habitat size = more diversity
↳ remove habitat completely = species are gone
↳ disturbance (storm/fire)-recolonization of species· not lost forever
Species Interactions
interspecific interactions -between species
↳ mutualism (H/t)-both benefit from interactions (ex. cleaner wrasse-cleans bigger fish, oxpeckers -eat ticks
↳ parasitism/disease (+/-)-parasite attaches to a host, takes resources, parasite-larger (ticks), disease -bacteria/virus > parasite-adapt to be hidden, stay on the host, not kill quickly
↳ herbivory (tH-plants eaten by something, plant-special features (taste, spiked don't die always
↳ Commensalism (10)-not many examples
↳ predation (+ -)-one species eats another
-interactions can lead to attributes, and repeated interactions create selective pressure (predator to kill, prey to live)
-coevolution dynamic, "arms race "
-features: weaponry (structures), speed, endurance, strength, camouflage, intelligence, agility, social
-influence the composition of a community
↳ relative abundance -dictated by the availability of resources + species interactions, amount /numbers of each species
- Food chain energy is taken into plants, plants eaten, species eaten, and contin…
-links connection of species
-exchange of energy -energy--biomass -> > consumed -biomass
-10% of energy moves to the next level -controls relative abundance, energy will run out, higher level: less abundant
-trophic levels -levels of species in the food chain
-primary producer -> primary consumer -> > secondary consumer -etc., more like web
-decomposer-cycles biomass/energy into lower trophic levels
-species in communities with influential roles on others, abundance dictates the abundance of others
↳ dominant species -most biomass (ex. algae disappearance = community collapse
-bottom-up control -abundance in lower trophic levels influences upper levels
↳ keystone species -pivotal role, no replacement, necessary for relative abundance
-ex: sec offers each urchin (hurt community)Lotters die from humans + whales /
-top-down control -influence lower trophic levels
↳ how species abundance influences one another - community dynamics
-intrinsic/biological facets also determine abundance
Intraspecific interactions -within species interactions
-population ecology-population growth outside other species
- change in population/change in time: r = b - d, r(N) = change population/change in time
-births (add population)+ deaths /lower population
-govern rate of increase
↳ bacteria = high, human/whales-how
-exponential growth -only births + deaths
↳ intrinsic rate of increase by biology ↳ ex. Birds
↳ could be undiscovered niche now discovered = growth
-cost of reproduction/influence of birth
↳ age at reproduction ↳ number gametes G resources available ↳ energy for care
-influence death: life span, competitors, diseases, etc.
-a certain number of offspring has the greatest fitness benefit
↳ manipulate number of bird offspring = Survival of parents impacted
logistic growth model
-modify exponential growth: P/T= r (N) · [(K-N)/K]
-populations cannot grow forever, resources can have limitations
-K = carrying capacity -limitation to population size in community may change over time due to resources
↳ N closer to K = equation = 0, N further from K = looks like exponential curve
↳ represents a modification of r, fastest in middle
-influence birth + death rates: -mostly death rates, birth rates are pretty set
↳ resources/competition -territory/area
↳ disease
↳ predation
-population growth generalization
↳ populations rarely stable at carrying capacity (ex. wolves + moose, wolves eat moose, cause/effect, wolf high - moose lovers, + wolf-lower
-heir + links -> > link eat heir -heir lowers -link lovers -heir higher
- low density
↳ relative abundance is low
↳ death rates low -more resources available fewer predators
↳ able to have more offspring
↳r-selected -select for high rates of increase (ex
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