biology assessment 1

Selection pressures

• External agents which affect an organism’s ability to survive in a given environment.

• Can be negative (decreases the occurrence of a trait) or positive (increases the population of a trait).

• May change over time, leading to changes in what constitutes a beneficial adaptation.

• Can be density-dependent (affected by population size) or density-independent (unaffected by population).

Types of selection pressures include:

Resource availability – presence of sufficient food, habitat (shelter/territory) and mates

Environmental conditions – temperature, weather conditions or geographical access

Biological factors – predators and pathogens (disease)

Types of landforms:

Biodiversity

• A variety of all living things and their interactions, present in one area. 

• Types: genetic, species, ecosystem 

• https://classroom.google.com/c/NjU4NjExMDAwMDMx/m/NjU4NjEyODQ0NzU1/details

Population Growth/Reduction 

• Factors: reproduction, migration, and death rates

• Limited resources, limited habitat space, sex ratio for mating

Adaptations: 

• A feature produced through natural selection for its current function. 

• Not all traits are adaptations.

• Any alterations in the structure or function of an organism or any of its parts that result from natural selection and by which the organism becomes better fitted to survive and multiply in its environment. 

Questions to assess adaptability

1. Is it heritable?

If a trait has been shaped by natural selection, it must be genetically encoded — since natural selection cannot act on traits that don't get passed onto offspring. 

2. Is it functional?

If a trait has been shaped by natural selection for a particular task, it must actually perform that task. 

3. Does it increase fitness?

If a trait has been shaped by natural selection, it must increase the fitness of the organisms that have it — since natural selection only increases the frequency of traits that increase fitness.

3. Galapagos Finches

Case study 

1. Name the organism

2. Name the characteristic

3. Describe the characteristic

4. Describe the environment

5. Explain how this characteristic gives a benefit to the organism’ survival in the environment it inhabits. 

Types of adaptation

1. Behavioural - things an animal does

• Migration, hibernation, mating dance, moving with the herd

2. Structural - parts of the animal 

• Shape of a bird’s beak, colouration, having wings

3. Physiological - processes within the animal

• Cellular respiration, life cycles, ability to produce venom

Ecosystem

An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, sun, soil, climate, atmosphere). 

Abiotic factors

• Non living physical and chemical elements in the ecosystem. 

• Usually obtained from the lithosphere, atmosphere, and hydrosphere. 

• E.g. water, air, soil, sunlight and minerals

Biotic factors

• Living or once living organisms in the ecosystem

• Obtained in biosphere and capable of reproduction

• E.g. animals, plants, fungi and other similar organisms. 

Biotic impacts

• The impact of biotic factors in the ecosystem

• Key impacts: predation, competition, symbiotic relationships

Competition

• Rivalry between or among living things

• Sources/causes: resources, mates, shelter, and space

• Interspecific competition: occurs among organisms of different species

• Intraspecific competition: occurs among the members of the same species. 

Symbiotic relationships

• A long-term, close interaction between two or more biological species. 

• Predation, Parasitism, Commensalism, Mutualism

Predation

• A symbiotic relationship between two organisms of different species in which one of them is a predator that captures and feeds on the other (prey). 

  • Use food chains and food webs

• Etc. cat and mouse, fox and bandicoot

Parasitism

• A symbiotic relationship between species, where one organism (parasite), lives on or inside the host organism, causing it some harm, draining it of its resources. 

• Etc. ticks and deers, ticks and humans

Commensalism

• A symbiotic relationship in which one organism benefits from the other organism, but doesn’t harm it in the process. 

• Etc. barnacle and a whale, sea anemone and clownfish

Mutualism

• A symbiotic relationship in which two organisms benefit from each other. 

• Etc. Honeybee and plant, bacteria and human

Abundance

• The relative representation of a species in a particular ecosystem. 

• Usually measured as the number of individuals found per sample.

• Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in the area. 

Distribution

• The manner in which the population of a species is arranged/located within an area.

• i.e. where the members of the species are locate

• Vary because of abiotic and biotic factors