populations Flashcards
(12 cards)
what is the carrying capacity?
every individual have the potential to do what?
so?
what is this called?
-the maximum stable population size of a species that an ecosystem can support
-to reproduce offspring to contribute to population growth but there are many abiotic and biotic factors that prevent an individual from reaching adulthood and reproducing
-the population size of each species is limited at some point = the carrying capacity of that species is reached
-the combined effect of limiting factors that prevent the further increase of a population is known as environmental resistance = on a graph = plateau
abiotic factors affecting population size?
example?
-non-living parts of an ecosystem:
•light availability
•water supply
•water mineral content
•temperature
•amount of space available
•soil pH
-if the mammal’s surroundings are a higher temp than optimum body temp = more energy to maintain optimum body temp = less energy available for growth and reproduction so fewer individuals reach reproductive age = population growth is limited
biotic factors?
3 types?
what can interspecific competition lead to?
-living parts of an ecosystem = interactions between organisms eg competition for resources
•interspecific competition (between different species)
•intraspecific competition (between different members one species)
•predation
-both populations are limited
• as each species has access to fewer resources and therefore less chance of survival
•happens when the two species are similarly well-adapted to the habitat
-can also lead to a decrease in population size of one species and an increase in population size of the other
•happens when one species is able to put-compete the other for resources = can reproduce
•occurs when one of the species is better adapted to the habitat
•eg = grey squirrels have increased and red squirrels have decreased
interactions between populations-
intraspecific- what happens when more individuals compete for the same resources (food and shelter)?
interspecific - eg grey and red squirrel = the native red squirrel was out competed for food and shelter, ALSO?
what have conservation efforts done?
-the resources become limiting and the population can no longer grow in size = the carrying capacity has been reached
-the grey squirrel carries a disease that is harmless to itself but can be fatal to the red squirrels
-in northern england and Scotland have slowed the spread of the grey squirrel by:
•protecting the red squirrels habitat and food
•giving the red squirrel legal protection
•re-introducing the pine marten = a natural predator of the grey squirrel
the 3 effects of competition-
competitive exclusion?
resource partitioning?
character displacement?
competitive exclusion - if two organisms occupy very similar niches = comp can exist between them for resources
•one species might be slightly better adapted to compete than the other so the other could starve or not find a habitat
•so wouod find a different niche = evolve to adapt to new niche over generations
resource partitioning - a particular resource eg a fruit tree is divided up to satisfy the needs of different feeders
•the fruit may be grazed by one species, the leaves by another
•if two species are not competing directly for the fruit tree but coexisting on different parts of it
character displacement - closely related species that inhabit the same geographical region and occupy similar niches species that differentiate in order to minimise niche overlap
•this avoids competitive exclusion
•eg beak size and shape in galapagos finches depending on species
•eg small and large seeds
•natural selection favours those species that compete less with other species
predation-
what is it?
what happens in a stable community?
example?
-consumers that kill and eat other animals, those eaten are known as prey
-the numbers of predators and pray rise and fall in cycles = limiting the population sizes of both predators and prey = predator-prey cycles
•number of predators increase and there is more prey available
•number of prey then decreases as now more predators
•as number of predators decrease, now less prey available
•so, the number of prey increases as fewer predators
•cycle now repeats
conservation and preservation-
what have humans done?
so?
done this by using:
-been successful in colonising every continent and many harsh habits = the human population has grown and is still in its logarithmic growth phase
-in order to not outcompete many species, humans have to adopt the role of environmental custodian = so manage sustainability and biodiversity for the future generations
-ecological techniques = conservation and preservation
what is conservation?
what is preservation?
-maintaining biodiversity and sustainability
•by allowing changes to the profile of organisms in ecosystem
•allowing human activity alongside other species in a managed way
-maintaining habitats and populations exactly as they are now
•making no allowance for usage by humans
•takes place at in small geographical areas with little or no human population but allows no human intervention
•eg areas of arctic tundra where mineral mining has been prohibited
reasons for conserving biodiversity:
•people believe humans have a moral obligation to prevent manmade loss of biodiversity
•the supply of important natural resources eg wood for construction
•employment
•supply of food for humans
•economic benefits to individual countries
•we are the most intelligent species so we are responsible to protect and value all of the organisms
what are the ecological reasons?
what are keystone species?
-a more diverse ecosystem is better able to survive and adapt to environmental changes or threats
•eg some fish may not be able to cope to the changes of global warming
-they have a larger impact on the ecosystem than others
•so when these are lost there are several knock-on effects
•eg bush elephants graze on a very extreme way; knocking over and eating several tree species
•this destruction of vegetation helps to maintain the ecosystem
•elephant dung = habitat for insects
•but when hunted for ivory = numbers reduce and negatively impact the savannah
what are the environmental reasons?
such as?
-humans need diverse ecosystems because of the essential environmental services they provide
•plants absorb carbon dioxide from atmosphere and reduce the greenhouse effect and climate change
•microorganisms digest and breakdown the masses of organic waste that are produced by larger organisms
•humans have irrigation and drinking water because of the transpiration of plants and contribution to water cycle
•different fungi and bacteria species are part of nutrient cycle for further plant growth
•plants are producers in food webs, both a direct and indirect energy source for humans
economic reasons?
why?
aesthetic reasons?
ethical reasons?
social reasons?
-ecosystems have a lot of economic value
•many of the medicines used today have originated from plants, fungi and bacteria
•ecotourism is a major source of income = travel to national parks and spend money, providing jobs
•also contributes to science and technology as taq polymerase was found in hot springs
-pleasure in the beauty of nature = inspiration for artists, photographers, poets
-humans have a moral obligation to prevent loss of biodiversity, they have no right to cause extinction of other species = responsible
-people enjoy spending time in the natural environment = can climb, walk, so such environments may be lost if not conserved = with the loss of social benefits they can bring
