NRC 261 1st Edition Outline of Last Lecture I Movement Home Range Lecture 11 A Home Range B Travel Paths C Areas of Frequent Use II Movement Patterns a Range Residents b Migrators c Nomads III Social Interactions Land Use a Territoriality IV Social Interactions Family Life Outline of Current Lecture II Species Distribution III Species Interaction IV Competition a Responses to Competition b Solutions to Competition V Case Study East African Jackals and Patagonian Foxes a Morphology b Behavioral Overalp c Prey Diversity VI Competition Case Study Gray Fox a Study Area b Objectives c Methods d Result s VII Conclusion s Current Lecture Species Interaction How is it that wolves coyotes and red foxes cougars lynx and bobcats black bears and grizzly bears and wolverines can all co exist in the Greater Yellowstone Ecosystem Species distribution if they interact they must have similar distribution and occur in the same places Allopatric species distributions do not overlap there is no chance for them to interact Sympatric species distributions do overlap chance for interaction Example ground squirrels in Texas Allopatric or Sympatric Species Black tailed prairie dogs only occur in short grass prairies Rock squirrels live in rocky areas definitely not prairies Mexican ground squirrels live in brushy but also grassy areas rocky areas that have brush grassy areas that are short grass prairies could say that on a much smaller area that Black tailed prairie dogs and rock squirrels are allopatric because when you look at a landscape they don t live in the same patch or landscape They likely don t live together Mexican ground squirrels may be able to live in other areas so they could be sympatric with both of the other species Characteristics physical appearance distribution maps parts of central texas and west texas where they overlap you could say that there is a large swatch of Texas where they appear to by sympatric they occur in the same counties if you re talking statewide important to be thinking about are two individuals actually living in the same spot with overlapping home ranges but sometimes all you need to know is on a bigger scale like if all three occur in the state of Texas Species Interactions 1 neutralism o o Bat species mouse species both live in same patch of forest neither species care about the presence of the other and they don t interact they happen to be small mammals and occur in the same place 2 commensalism o oxpeckers rhinos oxpeckers pick ticks off the rhino rhino provides them with potential food source but rhinos get nothing from the oxpeckers but they tolerate it definition it helps one is positive to one but doesn t do anything to the other 3 predation lion wildebeest what s good for the lion in the interaction is NOT good for the wildebeest parasitism sea lamprey lake trout lamprey latch onto fish and suck juices out which is harmful to the lake trout one wins and one loses 4 mutualism symbiosis ants acacia trees acacia have thorns that can be hollow which provide home for ants good for ants benefit for acacia tree is that when a predator comes to feed on the acacia tree the ants come out of the thorns and starts biting the predator one provides something for one the other provides something for another the cooperation badgers coyotes when hunting ground squirrels badgers dig holes coyotes chase squirrels in coyotes watch for squirrels to come out of other holes and the idea is that they chase them back in towards badger 2 different species working together to get the same benefits 5 competition spotted hyena lion each steal kills that the other makes both large carnivores that kill their prey potential for bad things to happen to both of them Competition Competitive exclusion principle The probability that two or more competing species may coexist in the same area is inversely proportional to their niche overlap probably that they re gonna exist depends on niche overlap if they completely overlap they re not going to coexist if they live in the same place but there s very little that once species uses that the other one does too then the likelihood that they ll coexist is fairly high no two species can have the exact same niche and live in the same place Responses to Competition ways that animals make sure they have different niches Numerical consequences different reproduction and survival rates some might not reproduce as well or not as many might survive different density and distribution at different places Functional changes morphological in order to get along over time they had to change their physical parts behavioral can behave in a different way when they re competing with a species vs when they re not competing Solutions to competition Avoidance morphological solution Character displacement evolution of physical differences to allow exploitation of different resources competition drives evolution something that different that does really well will survive more and those characteristics will survive in the population and eventually the population will evolve to be different ex Galapagos Finches Darwin very isolated on these islands opportunity because of variety of resources an no competition from other species caused them to evolve into several different species island with different mixes of species are shown in diagram top island has all 3 different species the next island only has two and the last two only have one each measurement differentiation was beak length and beak depth some have larger thick bills more depth and some have longer smaller bills more length the reason they re able to survive is that there are nuts insects seeds all of different sizes Ones with big bill can utilize food that others can t use different food and all three have evolved to best utilize food of different sizes some medium sized birds with big ish bill don t have to worry about competing with the much larger one so they can evolve slightly larger bills on the second island without any big billed birds but both medium and small billed birds on the island with just medium billed birds since there is no competition from the birds with the slightly smaller bill they re able to taken advantage of a better array of food sources and some grow smaller beaks when competition isn t there they evolve a particular way when competition is there they evolve a different way there are morphological characteristics of animals directly tied to food sources and competition can