topic 2.1 species and populations · •a group of organisms of the same species which live in the...
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Topic 2.1Species and Populations
Abiotic• Abiotic factors are the nonliving, physical
factors that influence the organisms and the ecosystem.
• Examples: temperature, sunlight, pH, salinity, and pollutants
Biotic• Biotic factors are the living components of an
ecosystem organisms, their interactions or their waste that directly or indirectly affect another organism
Species• A group of organisms that can interbreed to
produce fertile offspring
• Ex: Tiger
• Non-example:
Male lion and
female tiger
breed to produce a
Liger, which is sterile.
Population• A group of organisms of the same species which
live in the same area at the same time and which are able to interbreed.
• Ex: Meerkats in the savannah.
• Non-example: Meerkats that live too far apart to interbreed.
• 1 species of snails in 1 pond is a different population from the population in the second pond.
Habitat
• The environment in which a species usually lives.
• Ex: for the meerkats, it is the savannah and their meerkat burrow.
Community• A group of populations which live in the same
habitat and interact with each other. Communities contain all the
Biotic components of a
Habitat.
• Example: A community of
meerkats includes
Populations of
giraffes, trees, and grasses.
Ecosystem
• A community of interdependent organisms and the physical (abiotic) environment they inhabit.
Niche
• The particular environment and lifestyle that a species has. It includes factors such as the place where the organism lives and breeds, its food and feeding method, its activity patterns and interactions with other species.
• A niche is unique to each species, and offers the exact conditions that a species needs or has become adapted to.
• Two different species cannot occupy exactly the same niche.
Fundamental Niche
• Describes the full range of conditions and resources in which a species could survive and reproduce
Realized Niche
• Describes the actual conditions and resources in a which a species exists due to biotic interactions.
Example: lions and cheetahs both live in the same area of the African savanna but they hunt different prey. Lions take down bigger prey
Carrying Capacity
• The number of individuals of a population that the resources in the environment can support for an extended period of time.
• What could be a reason that individuals of a population would not be supported?– COMPETITION.
• What are some resources that individuals would compete for?
Limiting Factors
• When a demand for a particular resource is greater than the supply, the resource has become a limiting factor.
• Common limiting factors – space, light, food, nutrients, and water.
Intraspecific competition
• Intraspecific competition = competition between members of the SAME SPECIES for a resource.
Intraspecific competition• Increases as population numbers increase
• Eventually…population grows and reaches the carrying capacity
• Then, population growth rate will slow down as organisms…
– die from lack of an essential resource
– fail to breed and birth rate falls
Intraspecific competition• Different species respond in different ways:
– Frogs: if food is scarce, reduce growth rate & reach maturity at smaller size than normal
Intraspecific competition• Different species respond in different ways:
– Caterpillars: If all emerge together, compete on limited # of leaves, none are able to get enough food, and most will die.
Intraspecific competition• Plant Competition: limited by light, temperature and
carbon dioxide (basic requirements for photosynthesis)
– Also compete for space to extend roots (to obtain H2O and nutrients from soil)
– Light: some plants will grow faster and taller to beat rivals
• Limiting factors – prevent a community, population or organism growing larger. There are many factors which restrict the growth of a population
• Temperatures
• Food
• shelter
Ecological Interactions
Predation
When one animal, the predator, eats another animal, the prey.
Herbivory An animal (herbivore) that eats plants. Some plants have defenses for this. Herbivores can be large and small.
Competition
Two species compete for the same resource.
Symbiotic Relationships• two or more distinct organisms living
together for the benefit of one or both.
• 3 types:
• Mutualism
• Parasitism
• Commensalism
It is a popular assumption that algae in particular form a symbiotic relationship with the sloth, obtaining shelter and a good supply of water as sloth fur absorbs water extremely readily, and providing in return camouflage and extra nutrients via diffusion and absorption through the hair and skin.
https://www.youtube.com/watch?v=zSmL2F1t81Q
• Symbiotic Relationships
Parasitism
relationship between organisms where one organism (a parasite) lives or feeds on the other, usually causing harm.
A leech is a parasite that latches onto an organism with its suckers. While feeding on its host, the leech releases hirudin which is an anticoagulant which prevents blood from clotting. It also releases an anesthetic to prevent its host from noticing it to quickly.
In an interaction between a leech and a human, the leech gains food from the human, while the human loses blood.
Commensalism
• relationship between organisms where one organism benefits from the association while not harming or helping the other.
The cattle egret is a common species of heron it is mostly seen moving along with herds of cattle. This bird moves about in the pastures, and follows livestock such as cattle and horses. The cattle egret eats up the insects hiding under vegetation close to the grounds, which get stirred up when the cattle walk through them.
The remora, also called suckerfish, belongs to a family of ray-finned fish. It is a small fish growing up to a size of 1 to 3 feet. The remora forms a special relationship with sharks and other sea organisms like whales and turtles. It has special suckers attached to its fins. It attaches itself to the bodies of sharks, and uses the shark for transportation as well as protection from its predators. It also eats up the scraps of food that are left over when the shark eats its prey.
he barnacles are a type of crustaceans that are sedentary, i.e. they cannot move on their own. At their larval stage, they stick to the bodies of other organisms like whales, and other places like shells, rocks, or even ships, and grow on their surface. While the whales are on the move, the barnacles catch hold of floating plankton and other food material using their feather-like feet. This way, they get the nutrition and transportation, and the whale is not harmed or benefited in any manner.
https://www.youtube.com/watch?v=Mxpa6gPIbLE
• Commensalism video
Mutualism
• relationship between organisms of different species, in which both organisms benefit from the association.
Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers get food and the beasts get pest control. Also, when there is danger, the oxpeckers fly upward and scream a warning, which helps the symbiont (a name for the other partner in a relationship).
Egyptian plovers and crocodiles have a unique symbiotic relationship. Crocodiles can’t use dental floss, they get food stuck in their teeth. All that food rots their teeth and probably causes some pain. When a crocodile feels the need for a good tooth cleaning it will sit with its mouth wide open. The Egyptian plover bird sees the invitation, and if one is nearby it will fly into the mouth of the crocodile, eat the food stuck in its teeth, and fly away unharmed.
https://www.youtube.com/watch?v=ZOfN_JTexTc
://video.nationalgeographic.com/video/clownfish_amonganemones
S and J curves
• Population growth curves
• Show various stages of development of population over time
J curves• Population growth that does not slow down
– Birth rate is high
– Death rate is low
• WHY?– Pop. becoming established in new habitat
– Habitat may contain abundant resources
• Curve is J shaped – Starts with period of slower growth
– Rises sharply as more and more individuals join the population
J curves• J curve continues as long as resources
don’t become exhausted
• Typical growth curve of microbes, invertebrates, fish, and small mammals.
• What happens if the population overshoots carrying capacity?
S curves• Population has rapid, exponential
growth in initial stages
• As population grows, increase slows down (limiting factors)
• Eventually, population stabilizes at a level which the environment can support (carrying capacity is reached).
S curves
What type of population curve is the red line?
What type of population curve is this?
World population curve• What type of curve is this? What is
happening with our human population?
• What do you think WILL happen eventually?