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Bio 1309 Intimate Partnerships How Species Adapt to Each Other Slide 1 Adaptive Evolution • Adaptive evolution = natural selection acts on genetic variation in a population • Organisms with best adaptations for that environment have more offspring than other members of their species Slide 2 Species Effects • Natural selection = result of environment – (not just physical, also biological) • Other species around us have effects in addition to environmental physical components Slide 3 Species affect evolution • How different species affect each other’s evolution Slide 4 Orchid Example Fool Me Once… • Orchids are mean • Most plants offer a reward to their pollinator(s) – – – – Nectar Pollen Oil bodies Sex Slide 5 Orchid Example Sex mimic… • Sex you say?!? • Some species of orchids trick their pollinators by mimicking females of the species Slide 6 Orchid Example The wasp… • Lissopimpla excelsa – Orchid dupe wasp • Native to Australia – Pollinates all five Australian members of the orchid genus Cryptostylis Slide 7 Orchid Example Fools Male Wasp… • Shaped like a female wasp • Looks like a female wasp • Smells like a female wasp • Emits pheromones that mimic female wasp pheromones Slide 8 Orchid Example Male pollenates… • Male wasp fooled! (thinks flower is female wasp and attempts to mate - in process, picks up pollen • When male wasp tries to mate with another flower, pollen transfers Slide 9 Orchid Example pseudocopulation… • Pseudocopulation: Male wasp extends genital claspers into the flower and deposits sperm on the flower Slide 10 Species Relationships Predators, Parasites, Deceivers & Their Victims • The relationships between different species are diverse and varied: – Shrimp that clean fish – Cuckoos that trick other birds into raising their young Slide 11 Positive-Negative Predators, Parasites, Deceivers & Their Victims • One way to organize this diversity of relationship: measure the effect one species has on another species fitness – Effect can be: • Positive • Neutral • Negative Slide 12 Positive-Negative Predators & Prey • Predators and prey have a positive-negative relationship – Predators depend on their prey as a food source – Predators can reduce their prey’s fitness to zero Slide 13 Positive-Negative Parasites • Parasites can also have a positive-negative relationship with their hosts – Parasites may kill or weaken their hosts as they multiply Slide 14 Positive-Negative Fitness is about reproductive success! • Not necessary for organisms to die to have its fitness lowered by another species – Fitness is not just about survival • Ultimately, fitness is about reproductive success Slide 15 Positive-Negative Parasitic barnacle • Parasitic barnacle, Sacculina – Host is a crab • Barnacle burrows into the crab’s body and grows tendrils throughout the crab’s tissues – Crab shows no signs that it’s being “invaded” Slide 16 Positive-Negative Parasitic barnacle (cont…) • Crab carries on normally- searching for food and eating • The barnacle destroys the crab’s sexual organs so it can no longer reproduce Slide 17 Positive-Negative Parasitic barnacle (cont…) • The Barnacle benefits because host no longer expends energy looking for a mate or having babies… just looks for food and eats! Slide 18 Positive-Negative Parasitic barnacle (cont…) • The crab, is at an evolutionary dead end because its reproductive fitness has been reduced to zero Slide 19 Positive-Negative Wasp – Orchid revisited • In the case of the wasps and orchids, evidence that fitness of the wasp may be lowered – Wasp uses sperm on orchids = Less sperm to fertilize female wasps Slide 20 Positive-Negative Wasp – Orchid revisited (cont…) • Relationship benefits orchid so Orchid’s reproductive fitness is increasing • Possible downside: Depends on wasps! (Can only be pollinated by the wasps) Slide 21 Positive-Negative Wasp – Orchid revisited (cont…) • Interactions between the wasps and the orchids change each species fitness = natural selection is driven in both species Slide 22 Positive-Negative Wasp – Orchid revisited (cont…) • Mutations that enable male wasps to distinguish between orchids and real female wasps should be favored by natural selection Slide 23 Positive-Negative Wasp – Orchid revisited (cont…) • As wasps improve their sense of smell, natural selection will favor orchids that match the smell of female wasp pheromones more closely Slide 24 Positive-Neutral Commensal relationships • Some species depend on other species for their survival • Have no negative or positive effect on the fitness of their partners – Positive-neutral or commensal relationship Slide 25 Positive-Neutral Commensals • Remoras hitch a ride by clamping onto sharks and other fish • When the host fish finds prey, the remora lets go • After the host finishes eating, the remora cleans up the scraps Slide 26 Positive-Neutral Commensal examples • Commensals are well adapted to their hosts, for example: Pitcher plants live in nutrient poor habitats but supplement their diet by capturing and digesting insects Slide 27 Positive-Neutral Commensal examples (cont…) • Mosquito larvae feed on the accumulated dead bodies of captured insects inside the pitcher – These mosquito commensals have evolved adaptations that allow them to survive in this plant stomach • They are so adapted that they can live nowhere else Slide 28 Positive-Neutral Commensal examples (cont…) • Birds follow army ant raids on a forest floor • As the ant colony travels on the forest floor, they stir up various flying insect species Slide 29 Positive-Neutral Commensals (cont…) • As the insects flee from army ants, birds follow the ants to catch and eat the insects = the army ants and birds are commensalistic because the birds benefit and army ants are unaffected Slide 30 Positive-Positive Mutualism • Mutualism = two species interact in a way that benefits both (relationship is mutually beneficial) Slide 31 Positive-Positive Mutualism examples • Soil fungi, called mycorrhizae, form a mutually beneficial partnership with plant roots – The fungi increase the surface area of the plant’s root system • Plant can absorb more water and dissolved nutrients • Fungi absorb some of the food the plant produces Slide 32 Positive-Positive Mutualism examples (cont…) • Relationship between the oxpecker (a kind of bird) and the rhinoceros or zebra • Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin Slide 33 Positive-Positive Mutualism examples • The oxpeckers get food and the rhinos/ zebras get pest control • Also, when there is danger, the oxpeckers fly upward and scream a warning, alerting their partner (helping escape from predators) Slide 34 Positive-Positive Mutualism examples (cont…) • Bacteria and humans: various species of bacteria live in the intestines of humans (normal flora). • Bacteria provide required vitamins • Help humans digest some foods Slide 35 Positive-Positive Mutualism examples (cont…) • Bacteria benefit by getting food and a safe place to live • Humans benefit from bacterial digestion and the vitamins they provide along with water reabsorption. Slide 36 Positive-Positive Mutualism examples (cont…) • Organisms in a mutualistic relationship evolved together = coevolution • Each was part of the other's environment, so as they adapted to their environment, they "made use of" each other in a way that benefited both Slide 37 Coevolution • Coevolution can often be diffuse - meaning a species evolves in response to its relationship with a large number of species – example: Some plant species can be pollinated by various pollinators Slide 38 Coevolution – Example • Coevolution can be specific (meaning two species depend on each other completely) For example: Yuccas are pollinated by specific species of moths Slide 39 Coevolution – Example (cont…) • Female yucca moths gather pollen from a yucca flower – Carries it to another flower – Chews a hole into the ovary of the yucca flower – Lays her eggs in the hole Slide 40 Coevolution – Example (cont…) • Rolls the pollen into a ball – Stuffs it into the hole – Goes on her way • Yucca flower gets pollinated • Baby yucca moth larvae have a source of food in the developing seeds Slide 41 Coevolution – Locks & Keys example • Species coevolution can mold the morphology of two species so species match up like lock and key, for example: Acacia trees are protected from herbivorous insects by ants Slide 42 Coevolution – Locks & Keys example (cont…) • Ants roam the tree’s branches and trunk looking for potential invaders • Chase invaders off • Trees grow hollow swellings on their branches and ants live inside Slide 43 Coevolution – Locks & Keys example (cont…) • In addition, trees produce a sugary nectar or oil bodies that feed the ants Slide 44 Locks & Keys Coevolution – example (cont…) • Leonardoxa spp. – African rainforest trees – 3 species • All guarded by their own species of ant – Openings to the swellings on each species of tree precisely match the size of the ant protecting it Slide 45 Evolutionary Trees Mirror • history of interacting species seen in their evolutionary trees Slide 46 Evolutionary Tree Mirror example • Species of gophers carry particular species of lice • Compare the evolutionary trees of the gophers and lice = mirror-like symmetry Slide 47 Evolutionary Tree Mirror example (cont…) • Suggests that when a species of gopher splits into a new species, the lice that live on it diverge into a new species, too Slide 48 Mirror Trees • Mirror trees can also be used to shed light on the steps it took for a particular relationship to evolve • Sharpshooters and their bacteria – Insects that live on the fluid in plant xylem Slide 49 Mirror Trees – more examples • Sulcia and Baumannia are 2 bacterial species that help sharpshooters digest the xylem fluid • DNA studies on the insects and bacteria show that Sulcia was living in the sap feeding ancestor of sharpshooters 270 mya Slide 50 Mirror Trees – examples (cont…) • In more recent sharpshooter ancestors, Sulcia is joined by Baumannia inside the insects – Sulcia provides the insect with amino acids – Baumannia provides vitamins and other nutrients Slide 51 Mirror Trees – examples (cont…) Interesting symmetry: • Baumannia lost amino acid production genes except histidine • Salcia has retained amino acid production genes except histidine Slide 52 Bacterial coevolution! • the two bacteria coevolved with their host PLUS • They coevolved with each other! 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