study sheet for exams for bio class, Cheat Sheet of Biology

Download study sheet for exams for bio class and more Cheat Sheet Biology in PDF only on Docsity! Lecture 1 (Predation ) Ecology Scenario #1 ● Provided guppies with two potential prey: ● Aquatic worms ● Fruit flies ● Varied the abundance of each prey ● Measured the amount and type of prey Consumed “Generalist” ● Some consumers have broad diets ● Select their food according to its availability ● Common in carnivores Scenario #2 ● How many fly species eat: ❖ 1 plant species ❖ 2-5 plant species ❖ >10 plant species “Specialists” 1. Some consume have narrow diets 2. Often involves evolutionary adaptations 3. Common in herbivores (especially insects) 4. Plant tissues often contains physical and chemical defenses Figure 1 ● Hare => Lynx ● Hare and lynx populations exhibit regular cycles ● Lynx lags behind hares Figure 2 ● Hare reproductive rate depends on population density ● Small populations have a higher Reproductive rate Calculate the prey Isocline: sac NV decreases because of aq high predation dN ® aq = /N-aNP g _ —* : r 0 =rN-aNP 3 St ees i Prey Isocline aNP = rN. s — —- zo _ o N increases because of aP=r a low predation ea P=r/a Prey Abundance (N) ef e Predator Isocline Calculate the predator isocline: ns m | Pincreases Qa ‘ba |_ because of dP © abundant prey —_ = baNP-mP 7 I dt 5 ; f To < 1 0 = baNP— mP 3 I ¢ I baNR= mR Ss i Pdecreases | baN=m 2 because of | a scarce prey | 1 N=m/ba [= }PreyAb Predator Isocline Magnitude of predator-prey cycles is constant xc Q | o & S prey predator 2 *& ; x 5 2 ies Wk- 4-3 ----| Prey Isocline s < ww te x 1 a2 2 J I < o 3 iL Time o i Fa Prey Abundance (N) [acd * Predator Isocline The only place where the ¢ 8 1 c 1 s 1 2 pea te Sao Prey Is 4 1 ‘ 1 3 2 1 ° | Prey Abundance (N) PRACTICE: Calculate isocline values given the following data: r=0.40 a=0.02 m = 0.80 b=0.50 EQUATIONS: P=r/a N=m/ba EXPLORE: What happens if you increase or decrease these parameters? r=0.40 a=0.02 m= 0.80 b=0.50 Find a scenario where: * Both isoclines increase - Both isoclines decrease * Only prey isocline changes * Only predator isocline changes Predator Abundance (P) Predator Abundance (P) T a populations do not cycle is where the isoclines intersect > stable equilibrium Predator Isocline be a ba = =r { Prey Isocline “| Prey Abundance (N) Te : = Predator Isocline be a ba exieteoteee a | cee Prey Isocline At point B, an increase in lynx is followed by a decrease in hares Limit imposed by intraspecific competition ee eee ee reel How do we add in interspecific competition? dN, | N, eM K, There are more individuals in the building (population) than just species 1 We need to account for these “extra” individuals when calculating how much Let's say this building has 100 rooms... “room” there is to grow If some of these rooms are being used as a pet hotel, there are fewer rooms for new tenants. How do we add in interspecific competition? dN; _ . ( N,+ un) N, is the size of the second population iN, U1 - ~T “dt K, a is the competition coefficient that tells you how many individuals of species 2 it takes to equal 1 individual of species 1 If a = 1, each individual of species 2 affects the population growth rate the same as an Increasing N, or o brings the individuallof species: 1 population closer to its carrying If « = 2, each individual of species 2 affects capacity (less room to grow) the population growth rate twice as much as an individual of species 1 If « = 0.5, each individual of species 2 affects the population growth rate half as much an individual of species 1 What can we do with these equation? Red dashed line represents the isocline for species 1. This is the line where the population for species 1 does not change in size. So, when population size is above the isocline then population moves towards its isocline over years (star moving towards isoclines) 1. Graph 2 2. Graph 1 Lecture 4 Positive interactions Key concept: Positive interactions are more important in stressful environments Positive interactions can increase a species ability to tolerate abiotic stress (extreme heat or cold) Positive interactions can increase a species ability to tolerate biotic stress (interaction of two species help to survive/benefit) Lecture 5 (Speciation) Evolution The Biological Species Concept “Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.” E. Mayr (1942) What are some problems with this definition that you can see? The difficulty of recognizing species ● How to assess whether populations are “potentially interbreeding”? ● What constitutes reproductive isolation? ― If individuals from different populations produce sterile hybrids, then they are certainly reproductively isolated. ― What if they produce partially sterile hybrids? Phylogenetic Species Concept “an irreducible cluster of organisms diagnosably different from other such clusters, and within which there is a parental pattern of ancestry and descent” STRENGTHS • It Contains Historical Components. • It provides specific criteria that can be diagnosed in natural populations. WEAKNESS • It is vague. What exactly is meant by “irreducible cluster” and “diagnosably different”? • Taken Literally And To The Extreme,it's absurd. General Lineage Species Concept species are metapopulations that exchange alleles frequently enough to comprise the same gene pool STRENGTHS • It describes the essence of what we mean when we talk about species. In principle it could be used for almost any organismal group. WEAKNESS • In practice,it is nebulous and impossible to apply Lecture 6 (Modes of speciation) How do allopatric and sympatric speciation differ? Speciation The process by which one genetically-cohesive population splits into two or more reproductively-isolated populations. Requires the disruption of gene flow and the evolution of reproductive isolating mechanisms. Isolating Barriers • Geographic: extrinsic properties of landscape that prevent gene flow • Allopatry (populations in separate non-overlapping geographic areas, ie. geographic barrier to gene flow) • Reproductive: features of organisms that prevent interbreeding • Barriers effective even in sympatry (populations are in the same geographic area) Modes of speciation Allopatric Speciation: ● Speciation with geographic isolation. ● Evolution of reproductive isolating mechanisms between populations that are geographically separated. ● Geographic separation is defined by spatial restriction of gene flow, not just physical distance. Genetic basis of postzygotic isolation • Bateson-Dobzhansky-Muller incompatibilties: arise from negative interactions at two or more loci • Populations accumulate allelic differences at two or more loci that cause genetic incompatibilities when combined in hybrids. Hybridization and gene flow between species Even when two populations are considered separate species, there may be some gene flow between them. If hybrids have reduced fitness compared to parents, then selection should favor traits that minimize the production of hybrids The classic view of speciation 1. Barrier to gene flow develops 2. Slow Accumulation Of Genetic Differences Through mutation, drift, and natural selection 3. Genetic Divergence Leads To Reproductive Isolating mechanisms as a by-product 4. Perhaps Secondary Contact,with some level of hybridization possible Based on this figure of Drosophila, when were species more likely to hybridize? When they had a genetic distance < 0.5. The speed of speciation: adaptive radiations Adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. It involves the differentiation of a single ancestor into an array of species that inhabit a variety of environments and that differ in traits used to exploit those environments. What precipitates adaptive radiation? ECOLOGICAL OPPORTUNITY: the invasion of unutilized ecological niches leads to rapid diversification, e.g., colonizing a remote archipelago, surviving a mass extinction. KEY INNOVATION: the acquisition of a novel adaptive trait (behavioral, morphological, or physiological) allows organisms to exploit previously unavailable ecological niches. Adaptive radiations are often characterized by: ● Ecological opportunity ● Acquisition of novel adaptive traits ● Competitive interactions among closely related taxa ● Parallel evolution ● Rapid phenotypic diversification Speciation in non-eukaryotes and asexual organisms ● Microbial organisms present challenges to species concepts developed for eukaryotes ● New species concepts in microbiology may provide valuable insight into the evolutionary history of eukaryotes Horizontal gene transfer makes classification difficult Describe two challenges with studying speciation in bacteria. 1. Instead of being neatly divided by species barriers bacterias They regularly try to adapt into a changed environment by changing their genetic material. They are unstable. 2. The genomes of microbes have been mixed together by horizontal gene transfer (mixed up genome, not precise) Lecture 8 (Species Interactions and Coevolution) What is coevolution? Two (or more) species: 1) exert selective pressures on each other, and 2) evolve in response to each other Because each species is evolving in response to the other, one important feature of coevolution is that the selective environment is constantly changing. When does coevolution occur? Selective pressure will be strongest when there is a close ecological relationship “Close” ecological relationship = usually specialists rather than generalists Coevolution can involve either positive or negative interactions that affect the interacting partners differently Just like any other evolution, need genetic variation and heritable variation Examples of ecological relationships that give rise to coevolution: Coevolutionary Arms Race “Arms race”/ antagonistic coevolution: Coevolving species have to constantly “improve” to meet each new adaptation with a “better” adaptation of their own • interacting antagonistically and exerting reciprocal directional selection Escalation Coadaptations become increasingly powerful, yet species are not any better adapted because the selective landscape is constantly changing. This is the Red Queen Hypothesis: - running as fast as possible just to stay in the same place Example of co-evolutionary arms race Taricha granulosa newts have powerful tetrodotoxins (TTX) that are secreted as protection from predators Thamnophis sirtalis garter snakes are the only major predator of this newt – they have evolved resistance to TTX Escalation Toxins produced by newts are hundreds of times more powerful that necessary to kill any other predator (including humans), but snakes are resistant Both Mullerian and Batesian mimicry involve coevolution. Do both partners benefit? ● Both partners benefit in Mullerian ● Both partners benefit in Batesian ● Both partners benefit in both ● In neither one do both partners benefit Figs and fig wasps are obligate mutualists ● The Wasp Enters The Fig through an opening, lays eggs in some flowers and pollinates others. ● Male and female wasps emerge and mate. ● Females Collect Pollen And escape, and search out a new fig to deposit her eggs. Fig-wasp mutualism and Co-speciation Figs and pollinator wasps show a very high degree of co-speciation Why is horizontal gene transfer an important factor in defining microbial species? A. Because horizontal gene transfer undermines most species concepts B. Because homologous recombination could be considered microbial ‘sex’ C. Because horizontal gene transfer transforms microbial genomes into mosaics that are difficult to study D. All of the above Polyploids are often an example of instantaneous sympatric speciation. Which of the following lends support to that idea? A. Polyploids are often larger than their diploid ancestors B. Polyploids usually cannot interbreed with their diploid ancestors due to chromosomal pairing problems C. Polyploids only form new species when they are geographically isolated from their diploid ancestors D. All of the above What type of coevolution produces an evolutionary arms race between a predator and its prey or a parasite and its host, which may go on indefinitely, producing a wide array of adaptations? A. Batesian mimicry B. Antagonistic coevolution C. Mutualistic coevolution Which is an example of a postzygotic isolating barrier? A . The hybrid offspring of two species of birds that can produce normal gametes but cannot obtain a mate B . Females of one kind of fly that are not attracted to the buzz of another kind of male C . Two species of bats breeding in different habitats D . Corals spawning (releasing gametes) at different times of day Under the biological species concept: A. A species represents a group of interbreeding (or potentially interbreeding) populations B. Different species are reproductively isolated from other such groups C. Different species do not exchange genes D. A and C are correct E. A, B, and C are correct