Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
43 Cards in this Set
- Front
- Back
|
Types of Interactions
|
1. +/- consumer-resource
- predator-prey, parasite-host, plant-herbivore 2. - /- competition 3. +/+ mutualism - trophic, seed dispersal, pollination, defense |
|
|
Types of Interactions
|
1. Competitive interactions
2. Antagonistic interactions 3. Mutualistic interactions |
|
|
Effects of Competitive Interactions
|
Competitive interactions lead to divergence
- The fitness of individuals of each species is decreased by the interaction→ reciprocal selection favors traits in each species that reduce the efficacy or frequency of the interaction - Divergence in traits mediating the interaction (i.e., character displacement) |
|
|
Effects of Antagonistic Interactions
|
Antagonistic interactions lead to cycles or escalation - the fitness of victim individuals is increased by not interacting while fitness of exploiter individuals is increased by interacting→ reciprocal selection favors victim traits that decrease the efficacy or frequency of interaction, but exploiter traits that increase the efficacy or frequency of the interaction
- Coevolutionary escalation – Reciprocal selection favors increased/decreased phenotypes in both victim and exploiter→ selection is directional - Without cost→ endless escalation of phenotypes; with cost → phenotypic cycles |
|
|
Effects of Antagonistic Interactions Continued
|
- Coevolutionary matching – Reciprocal selection favors exploiters that match the phenotype of the victim, but victims that mismatch the phenotype of the exploiter→ selection is time-delayed negative frequency-dependent
- Phenotypes cycle endlessly→ exploiter adapts to common victim phenotypes→ should produce an advantage for rare victim phenotypes → generate co-evolving polymorphism |
|
|
Effects of Mutualistic Interactions
|
Mutualistic interactions lead to convergence
- The fitness of individuals of both species is increased by interaction→ reciprocal selection favors traits in both species that increase the efficacy or frequency of the interaction - Selection is positive frequency-dependent - Coevolving complementarity in symbiotic interactions and coevolutionaty convergence in free-living interactions |
|
|
Biological vs. Physical Factors
|
-biological factors stimulate mutual evolutionary responses in traits of interacting populations: species act as selective agents on each other’s traits
-adaptations of organisms in response to changes in the physical environment have no effect on that environment - biological agents foster diversity: organisms tend to specialize - physical agents foster convergence - biotic selective agents evolve→ species act as selective agents on each other’s traits |
|
|
Fitness
|
- Production of descendants over an individual's lifetime
- Representation of your stuff in the future: send yourself and send your offspring - Survival and reproduction both determine your contribution to genes (and trait distributions) in future population |
|
|
Evolution
|
1. Selection= non-random association of fitness with traits; heritable traits that promote reproductive success are passed on at a high rate
- traits of those individuals that leave the most offspring are selected 2. Response to selection (IF there is a genetic basis to traits)= change in gene frequency and change in trait distribution across generations |
|
|
Coevolution
|
- when populations of two or more species interact, traits of each may evolve in response to traits of the other
- reciprocal selective effects on traits: adaptions of one species promote evolution of adaptations in the other - sequence of evolutionary responses resulting directly from the interaction between two populations |
|
|
Diffuse Coevolution
|
- evolutionary responses of each species to all others with which it interacts
- “coevolved” traits arise as responses of populations to selective pressures exerted by a variety of species, followed by ecological sorting - species are organized into interacting sets based on their adaptations, co-evolved or not - compared to pairwise coevolution: reciprocal evolution of related structures and functions in two interacting species |
|
|
Charles Mode
|
- 1958: coined the term coevolution after studying agricultural plants and their fungal pathogens
- host and pathogen: cycling of virulent/avirulent pathogens and susceptible/resistant hosts - fitness of the host and fitness of the pathogen are each contingent on genotype of the other |
|
|
Charles Mode Continued
|
- when the host is susceptible (rr), selection favors virulent pathogens (VV or Vv)→ virulent pathogens cause selection for host resistance (RR or Rr) which then increase in host population→ when host is resistant, selection favors avirulent pathogens (vv) because virulence is costly→ when the pathogen is avirulent, selection favors susceptible hosts (rr) because resistance is costly (r→V→R→v→r)
- modeled genetic and evolutionary mechanisms underlying relationships between consumer and resource populations |
|
|
Paul Ehrlich and Peter Raven
|
- 1964: placed coevolution into an ecological context
- closely related groups of butterflies tend to feed on closely related species of plants - Heliconius butterflies feed exclusively on passionflower vines of Passiflora→ suggested long evolutionary history linking the two - specialization is associated with host plant chemistry→ plants' secondary compounds (noxious compounds produced by the plant) determined the usage of certain plants by butterflies - interpreted patterns of relationships in nature as outcomes of evolutionary interaction |
|
|
Geographic Mosaic Theory
|
- Thompson 2005
- Argues that co-evolving interactions have three components that collectively drive ongoing coevolutionary change: 1. Geographic selection mosaics: selection varies among populations because there are geographic differences in how fitness in one species depends upon the distribution of genotypes in another species - often a genotype-by-genotype-by-environment interaction in fitnesses of interacting species 2. Coevolutionary hotspots: Interactions are subject to reciprocal selection only within some communities |
|
|
Geographic Mosaic Theory Continued
|
- these coevolutionary hotspots are embedded in broader matrix of coevolutionary coldspots, (where selection is non-reciprocal or where only one of the participants occurs)
3. Trait remixing: The genetic structure of coevolving species changes through new mutations, gene flow across landscapes, random genetic drift, and extinction of local populations - These processes contribute to the shifting geographic mosaic of coevolution by continually altering the spatial distributions of potentially coevolving genes and traits |
|
|
Heliconius Butterflies
|
- have big eyes and look for leaf shapes that match their template of what a suitable plant for egg laying should look like
- lay eggs on and caterpillars feed on nectar of Passiflora leaves→ store the plant toxins→ aposematic and distasteful - Show Miillerian mimicry that frequently crosses taxonomic borders within as well as outside Heliconius →mutualism that may also increase adult longevity by reducing predatory attacks by birds - Heliconius females feed on pollen from Anguria and Gurania (in squash family) flowers as well as nectar |
|
|
Heliconius Butterflies Continued
|
- high canopy vines that have bright, red tubular flowers with a bright yellow marking the center
- Pollen provides amino acids that can't be obtained from other sources and is used in egg production and contributes greatly to the longevity of the butterflies - Different Heliconius species lay eggs on different species of Passiflora but use the same pollen food resources→ hence their adult foraging behaviors are driven by competitive interactions - Very specialized |
|
|
Passiflora
|
- Passiflora leaf shapes and egg mimics are defensive against a visual herbivore:
- Butterflies normally only lay a single egg on each Passiflora (minimize competition between siblings for food and avoid canabilism ) so some Passiflora species adapted by producing tiny structures on their leaves or stems which mimic Heliconius eggs - Change leaf shape→ can't be recognized - Chemically protected by cyanogenic glycosides, which prevent most plant-eating insects from feeding on it - Trichomes→ leaves and stems are covered with a coating of sharp microscopic hairs which puncture the |
|
|
Passiflora Continued
|
skin of browsing caterpillars, rendering them immobile, and killing them by starvation
- Drooping growing tip which suggests to predators that the plant is in poor condition/wilting→ less appealing either as a snack or as a future food source for eggs that may then be laid elsewhere - Foliage which becomes toxic when attacked by herbivores, while fruits remain toxic until they are ripe - The variety of counterdefences shown by Passiflora serves to emphasize the point that coevolutionary interactions can result in increased variability |
|
|
Müllerian Mimicry
|
- occurs when several unpalatable species adopt a single pattern of warning coloration
- predators learn to avoid these mimics more efficiently because a predator's bad experience with a single species confers protection on all other members of the mimicry complex - aposematism: conspicuous patterns or colors adopted by unpalatable prey organisms to advertise their noxiousness or dangerousness to potential predators |
|
|
Passiflora and Heliconius Interaction
|
- Butterflies lay eggs on leaves, caterpillars eat leaves
- Plants produce toxins to reduce herbivory - Butterflies become resistant - Plants develop egg-like nodules - Butterflies avoid leaves that already have eggs |
|
|
Florida Firebush (Hamelia patens)
|
- Before dawn, the flowers begin producing nectar→ mites, bees, butterflies, and hummingbirds become competitors for the sugary liquid
- Mid-morning the flowers stop producing nectar - One or two mites will race up the bill of a feeding hummingbird and into the nares and will ride until the hummingbird visits another firebush flower where they disembark - Inside the nares, the mites are inundated with air moving into and out of the hummer's lungs and they may detect an aroma that neither humans nor hummingbirds can |
|
|
Florida Firebush Continued
|
- Fruit ripen and become attractive to birds faster when some fruit are removed than when all fruit are left on an infructescence→ more ripe fruit are presented to birds when dispersers are abundant than when they are scarce→ removal of fruit commonly stimulates growth in plants
|
|
|
Herbivory Overview
|
- related species of butterflies tend to feed on related species of plants→ plants evolve a new chemical defense which creates an herbivore-free adaptive zone in which the plants proliferate and speciate and eventually on or more insect species evolve a counter-adaption to this defense→ opens a competitor-free adaptive zone in which herbivores proliferate and speciate
- adaptive zone: region in niche space where a taxon is so successful that it proliferates into many habitats and speciates into multiple forms |
|
|
Herbivory Overview Continued
|
- Herbivore attack can induce dramatic changes in plant chemical defenses→ protect plants against future herbivory, but can also have important physiological and ecological costs
|
|
|
Evolution of Host Chemistry
|
- studied by Berenbaum
- increasing complexity and increasing toxicity of host→ increasingly specialized adaptions - ONLY highly specialized insects feed on the most toxic ones→ these are descended from close relatives that feed on less toxic ones - Insect families such as Swallowtail butterflies (Papilio thoas from Peru), that feed on carrot family also feed on distantly related Citrus family (which also has furanocoumarins) - The carrot family includes Queen Anne’s Lace, celery, cilantro, parsley, dill, ect. |
|
|
Evolution of Host Chemistry Continued
|
- evolution of toxic furanocoumarins created a herbivore-free adaptive zone favoring speciation in umbelliferous plants→ created a competitor-free adaptive zone in which Papilonidae butterflies could speciate due to their ability to detoxify the furanocoumarins
|
|
|
Furanocoumarins
|
- biosynthetic pathway: paracoumaric acid (found in virtually all plants)→ hydroxycoumarins→ furanocoumarins (linear and angular)
- increase in toxic and decrease in number of plants synthesizing these chemicals as move down path - LFCs interfere with DNA replication in presence of UV light and AFCs interfere with herbivore growth and reproduction in general - LFCs are a taxonomic subset of plants containing hydroxycoumarins and AFCs are an even smaller subset of those containing LFCs |
|
|
Mutualism
|
1. Trophic
2. Defensive 3. Dispersive - Each party is specialized behaviorally or physiologically to perform a function lacking in the other - likely start out as predator-prey/parasite-host/commensal relationships and natural selection acts on both partners to derive benefits from their association→ partners coevolve to exploit one another more efficiently to their mutual benefit |
|
|
Mutualism Continued
|
- Experimental genetics in the field can reveal how plant-animal interactions select for different genes and trait distributions
- Identification of coevolved relationships is difficult, preadaptations and geographic mosaics may complicate evolutionary interpretation |
|
|
Trophic Mutualism
|
- usually involve partners specialized for obtaining energy and nutrients
- lichen: partnership between algae and fungi - alga provides nutrition through photosynthesis and fungus provides support and protection from desiccation and solar radiation - Rhizobium-plants - bacteria form nodules on the roots of plants in the pea family (legumes); the nodules fix nitrogen and the plant provides the fungus with carbohydrates |
|
|
Trophic Mutualism Continued
|
- Mycorhizzae-plants
- fungi that bring nutrients (especially important in increasing plant access to phosphorus and other immobile nutrients ) to the plants in return for carbon; also capable of improving water uptake and communicating to their hosts to resist to pathogens - Wood digesters in rumens- bacteria within ciliates - bacteria digests cellulose in plant fibers (cow's own digestive enzymes cannot break down) and cow assimilates some of the by-products and metabolizes; the bacteria have a steady supply of food in a warm, chemically regulated environment that is optimal for their growth |
|
|
Defensive Mutualism
|
- involve species that receive food or shelter from their partners in return for a defensive function
- ant-plants: Acacias and Pseudomytmex ferruginea ants - plant houses ants and provided carbohydrate-rich food for them in nectaries at the bases of the leaves as well as fats and proteins in the form of nodules (Beltian bodies) at tips of some leaves - ants protect their host plant from herbivores and competing plants |
|
|
Defensive Mutualism Continued
|
- each has evolved adaptations to increase the effectiveness of their association:
- ant is active night and day in order to provide protection at all times - ants have a true sting and will swarm vertebrate herbivores that attempt to feed on plant - ants also clear away potential competitors by attacking seedlings near their host plant's base as well as any vines or overhanging branches of other plants - acacia retains it leaves throughout the year even though rainfall is extremely seasonal - Neither can survive without the other |
|
|
Dispersive Mutualism
|
- involve animals that: a) transport pollen in return for rewards such as nectar and b) transport and disperse seeds in return for the nutritional value of fruits or other structures associated with seeds
- seed dispersers-plants→ not highly specialized, partners are only loosely associated and may interact with a variety of species - pollinators-plants→ more restrictive because in plant's favor that a flower visitor carry its pollen to another plant of the same species) |
|
|
Pollination
|
- Mimulus lewsii: pink flowers that are quite open→ attract bumblebees ( 100% of pollinations by bees)
- Mimulus cardinalis: red flowers with a more narrow shape→attract hummingbirds (98% of pollination by hummingbirds) - grow at different elevations and each species has become adapted to that elevation - even in sympatry these species are isolated to a large degree by pollinators - locus, called yellow upper (YUP) that affects carotenoid distribution in the petals (dominant form prevents carotenoid deposition) |
|
|
Pollination Continued
|
- In M. cardinalis carotenoids are found throughout the petals and the flowers are red→ bees are not attracted to red flowers; produces lots of nectar and attracts hummingbirds
- hummingbirds have evolved long, narrow bill, and extendable tongue to facilitate nectar gathering - in M. lewisii results in less carotenoid and the flowers are pink→ flowers attract bees - when dominant YUP allele is bred into M. cardialis the flowers are pink and recessive YUP allele causes more carotenoid to be deposited making the flowers orange in M. lewisii→ bees preferred the pink flowers |
|
|
Pollination Continued
|
whether they were in an M. lewisii background or an M. cardialis background. Conversely, hummingbirds preferred the orange and red flowers in both backgrounds
- a significant decline in the bee population could have occurred in a small part of the range at the time the mutation arose leading to a subpopulation with red flowers - Pollinator-mediated selection on floral traits |
|
|
Yucca-Yucca Moth Mutualism
|
- adult female yucca moths carry balls of pollen between yucca flowers by means of specialized mouthparts→ during pollination, female moth enters the flower and deposits eggs (1-15) in the ovary→ moth then crawls to top of pistil and deposits bit of pollen on stigma (ensures that flower is fertilized and offspring will have developing seeds to feed on)
- after the eggs hatch, the developing larvae feed on some of the developing yucca seeds, not exceeding 30% of the seed crop |
|
|
Yucca-Yucca Moth Mutualism Continued
|
→the yucca exerts selective pressure on the moths (through abortion of heavily infested fruits) to limit moth genotypes predisposed to lay large numbers of eggs (cheaters)
- Moth larvae have no other food source and yucca plants have no other pollinator→ obligate mutualism |
|
|
Adaptations of Yucca and Yucca Moth
|
- Yucca: pollen is sticky and can be easily formed into ball, stigma is specially modified as receptacle to receive pollen
- Moth: individuals visit flowers of only one yucca species, mate with flowers, lay eggs in ovaries of flower, exhibit restraint in the number of eggs laid per flower, and have specially modified mouthparts and behaviors to obtain and carry pollen -Many aspects of the mutualism are present in the phylogenetic lineage of nonmutualistic moths within which Tegeticula evolved: host specialization and mating on the host plant, flower abortion |
|
|
Adaptations of Yucca and Yucca Moth Continued
|
- What appear to be coevolved traits may have been preadaptations that were critical to establishment of the mutualism in the first place
|
