Community Ecology and Climate Change

Community Ecology and Climate Change Community Ecology Competitive exclusion principle: When 2 species directly compete for a resource, they cannot co-exist, and one will dominate the other Niche Partitioning: Dividing a resource or niche by two competing species (ex: different bird species partition a tree) Resource portioning: alter the use of their niche to avoid competition by dividing resources among themselves Species interaction     Competition -/o Direct competition for resources and species tries to out compete one another Predation/ Parasitism +/ o One species eats another in predation ex: Lion eating a zebra o One species takes resources off the host and can make the host sick ex: tapeworms Mutualism +/+ o Animals work together and both benefit from the interaction ex: plants and fungi Amensalism o At first is positive for one species that harms or kills another species but then doesn’t benefit the one species anymore. Ex: black walnut trees Due to interactions species have adapted many ways to deal with interactions Camouflage: Defense mechanism in which an animal blends in with their surroundings. This can be used by both predator and prey with the main strategy of hiding. Aposematic Coloration: It is warning coloration that tells other organisms the truth to avert danger. The back up to threat is toxins which are usually not lethal so that a predator can learn to avoid coloration. This depends on the dose and target of the toxin Mimicry: Takes advantage of the defenses of another species and are usually not toxic or less toxic than the species they pretend to be 3 types:   Batesian mimicry: Harmless species that have the same warning coloration as a harmful species Mullerian mimicry: A form of mutualism in which species that are toxic share warning coloration to amplify the warning coloration effect for predators. Some are auditory or behavioral warnings  Emslayen/ Mertensian mimicry: This mimicry can only work if a predator can learn. If an organism is deadly the predator will never learn to avoid the organism. It can lead to deadly species mimicking a less dangerous species to benefit from its warning coloration Different roles in an ecological community:     Keystone species o A species with a disproportionate effect on the environment and biodiversity and when removed from the environment, it can lead to environmental decline and reduced biodiversity o Some strong examples: Wolves in Yellowstone, Otters in northern waters, Sharks in the oceans o When added back to a community, the biodiversity can rebound Pioneer species o First colonizers to a new area that can make the environment habitable for new species o They can do this by adding biomass, bringing organic material, and building up soils in terrestrial environments o Ex: Lichen, Mosses, grasses, or a mix of small plants Foundation species o Any species that changes or greatly affects the structure of the ecosystem o Often called the bedrock species because it creates niches other animals or organisms can use o Often producer species Ecosystem engineers o Animals that through their actions change the ecosystem and creates new niches ( roles in the environment) o Beavers building dams are a great example Biodiversity: A measurement of the variability of life on the planet Three Types: 1. Genetic 2. Species 3. Ecosystem Why is diversity important? High diversity is synonymous with an ecosystem’s health and high biodiversity means greater stability, productivity, and resistance to changes Biodiversity hotspots: They are areas with a high number of endemic species, which are not found anywhere else on the planet Measurements of species diversity:  Species richness: This is the # of different species in a community  Relative abundance: The fraction of life in the community accounted for by each species. It is also called species evenness. It is a measure of a community’s heterogeneity Types of Community Succession: Primary Succession:     Starts on bare rock No pre-existing life in the area Initial colonizers Must be able to start the ecosystem Secondary succession:     Occurs where life was Happens due to habitat destruction( things like fires and other natural disasters) The colonizer species can make use of the resources left by the previous community Is typically shorter than primary succession Both:    The community of organisms gradually over time changes End goal: the creation of a climate community Occurs over a long period of time Communities across the latitudinal gradient The tropics have older communities than in the more temperate zones which have allowed for more time for evolution This has arisen due to a lack of restarts in the community because of changes in the environment In addition, the greater sunlight and rainfall in the tropics has allowed for more energy in the communities Species Area Curve Larger environments have more species: Every organism needs a certain number of resources to survive Minium viable population: The smallest population necessary for a species to survive With more space in an environment, there is more resources and more chances for evolution to take place Island-Equilibrium Model: This model states that the larger the island the more species that can be found on it and the closer to shore it is the more opportunities for colonization from the mainland Climate Change How do we know about past climate change?     Ice Cores: The physical properties of the ice can tell you how it formed o Ice also traps things like gases, pollen, ash, and radioactive isotopes Geological record: This shows major events in the history of the Earth o It must be important if an event shows up in the geological record Tree Rings: Adding up successive tree rings can give a picture of recent climate changes o This is called dendrochronology o Thinner rings show less rain in a given year Historical/Cultural data o Economic records o Historical artwork o Data from natural events Effects of a changing climate on history The Medieval warm period:   This happened between 900-1300 and was a warm period where there was less sea ice This helped the Vikings conquer and invade the new world and a lot of Europe easily The Little Ice Age:    This occurred between 1550-1850 with some volcanic eruptions happening in other parts of the world This led to a drop by 1oC which led to longer winters This led to some scarcity of resource and may be a factor that led to European imperialism and colonization in search of resources. Current estimates of the climate change say it is occurring more rapidly due to human activity and could lead to greater troubles in the future if not dealt with.