Intro to Ecology Why are there so many different kinds of life Why are some kinds of life more common or more rare than others Why do some species share many characteristics while some share very few How do existing organisms adapt to a changing environment The theory of evolution explains only part of the answer to these questions It explains how organisms change and adapt to the environment in which they live We ve talked about how the organism but what about the environment All of the factors both living and nonliving that influence the survival Environment Environment defined and evolution of an organism Living factors Also called biotic factors Nonliving factors Also called abiotic factors Environmental Influences Environmental Influences The environment selects and thus directs the evolution of a population of organisms The field of ecology studies the environment in order to understand what the selection pressures are and why those Ecology Ecology is the study of the interaction between organisms and their environment Permanent feedback loop Actions of populations of organisms can affect the environment Environment selects most fit organisms and thus influences the development of the population Humans are no exception Levels of Focus in Ecology The world is a big place Different ecologists study different aspects of ecology by narrowing or broadening their focus Types of Ecology Population Ecology How groups of organisms of the same species interact Community Ecology Interaction of organisms of different species all living in the same place Ecosystem Ecology Interaction of all of the community plus the nonliving abiotic environment Ecology and Peppered Moths Population ecologists find that the dark colored moth is more common and the light colored moth is dying out Community ecologists Find that birds are eating the light colored form because they are poorly camouflaged Ecosystem ecologists Find that pollution from human activities is changing the color of the birds natural hiding places and naturally selecting dark colored moths Population Ecology The Texas Mosquito Mystery West Nile Fever Disease caused by West Nile Virus People become infected from bites of mosquitos that carry the virus In 2011 27 cases and 2 deaths 11 total from 2003 2011 In 2012 398 cases and 19 deaths Why were there so many more cases of West Nile in 2012 and not in 2011 Why did this happen in Texas and not in New Jersey This is a problem of population ecology The Texas Mosquito Mystery More mosquitos more bites more transmission of virus to humans Why more mosquitos Population Growth Remember from previously that populations grow exponentially It turns out that the population of mosquitos exploded in Texas in 2012 Blue line Food and other resources increase much more slowly Available resources limit the growth of the population Carrying Capacity In truth populations tend stay at a level called the carrying capacity K K the maximum population size that can be supported by available These factors food space mates predators etc are called limiting food space etc factors Note Limiting factors same as competition types Limiting factors selection pressures Leaky Bucket Analogy Every year more offspring are born hose but population water level stays same Leaks deaths Disease Predation Starvation Disasters If you can remove or change those limiting factors the carrying capacity changes Can move up or down Mosquito Limiting Factors Food Eat blood meals esp reproducing females Primarily vertebrates Horses Cattle Humans Mosquito Limiting Factors Predators Mexican free tailed bat Official state bat of Texas Lots of vertebrates in Texas in 2011 and 2012 so NO CHANGE Eats mosquitos More mosquitos more food for bats more bats mosquito population reduced Predators a LIMITING FACTOR but proportional to mosquito population Territory Territory Mosquitos lay eggs in stagnant pools of water Warm still few no animals to eat eggs Texas had a drought in 2012 Rains wash away eggs from stagnant pools Less rain more stagnant water more mosquitos Territory REDUCED as a limiting factor Reproduction Mosquitos are cold blooded Rate of reproduction low when temps cold high when hot Texas in 2012 had a hotter summer and unseasonably warm winter Reproduction REDUCED as a limiting factor population grows quickly Mystery solved Unseasonably warm temperatures and a lack of rainfall dramatically increased the rate of mosquito reproduction Since more mosquitos more infections this explains the increased infection rate Human Population Growth http www youtube com watch v E8dkWQVFAoA feature share list PL8dPuuaLjXtNdTKZkV GiIYXpV9w4 WxbX Community Ecology Ecological Communities Community defined Associations of two or more species of organisms that live in the same place and interact with each other All organisms Microorganisms Bacteria fungi etc Plants Animals Community Interactions Competition Multiple species using the same resources Killing eating another organism for food Predation Symbiosis Competition Long term close interaction between more than one species Can be helpful or harmful When multiple species in a community need the same resource they must compete for that resource If not enough for everyone competition leads to selection struggle for existence Most fit individuals pass on traits population evolves over time Types of Competition Exploitative competition Competition between individuals or populations for a common resource Space food light etc Who can best exploit use available resources wins Examples Barnacles Lion vs hyena competition for food Have same prey ranges Algal blooms Types of Competition Interference competition Direct physical or chemical interference between species Example Lion vs hyena Direct competition because they hunt the same prey Kill each other steal food steal kill babies http bit ly W3JWdm Another example hint antibiotic case study The winner of the competition survives and passes on its genes and traits The loser will either die extinction or move to a new place to live emigration The proper term for this outcome is competitive exclusion Competitive Exclusion In the wild Very rare mostly because of human intervention Invasive species Red squirrel top Common throughout Europe incl UK Eastern gray squirrel Introduced to UK in late 1800s No natural predators to limit population growth Better at competing for available food Red squirrels being excluded by gray squirrels Population shrinking