4.1 - 4.3 Niche

Habitat

The space where an organism lives

Population

- a group of interbreeding individuals of the same species found in an area

Community

all the various populations in a habitat

Species evennesss

the number of species within a habitat

Species richness

Number of individuals of each species

Endemism

Habitat diversity

• range of different ecosystems or habitats within a particular area or region

Habitat diversity: High biodiversity

The larger the number of different habitats within an area, the more likely it is to have a high biodiversity

Species diversity

• the number of different species in an ecosystem, and their abundance.

Benefits of High species divesity

• The higher the species diversity, the more stable the ecosystem is

• More resilient to environmental changes

Genetic diversity

• the variety of alleles in the gene pool

Gene pool

All the alleles of all the genes present in a population of a species

Causes of genetic diversity

• mutation

• Random assortment

• Crossing over

• Populations occupy different ranges, different selection pressure, different allele frequencies

Genetic diversity importance

• helps population to adapt to, and survive, changes in the environment

Causes of low genetic diversity

• inbreeding in small isolated populations can lead to a high proportion of homozygous individuals, resulting in lower biodiversity

• Genetic disease caused be recessive alleles are more common in a population.

Human factors affecting biodiversity

• Habitat destruction

• Overexploitation

• Hunting

• Agriculture

• Climate change

How has variety of life changed over time?

• Variety increases as new species form

• Human activity is threatening much of the life on the planet.

Distribution of a species

• how a species is spread throughout the ecosystem

Species abundance

• the number of individuals of that species

Random sampling

• Using quadrats, convert sampling area into grid format

• Label each square

• Use a random number generator to pick sample points

• Record the organisms and numbers

Other sampling techniques to for animals

• Sweeping nets

• Pitfall traps

• Kick-sampling

ALWAYS USE SAME SAMPLING METHOD

ALWAYS USE SAME SAMPLING METHOD

Measuring genetic diversity with phenotype

• Different alleles are responsible for the variety of phenotypes within a species

• The greater the variety of phenotypes within a species, the higher the genetic diversity

Measuring genetic diversity with genotype

• An organisms genotype is determined by the different alleles found within cells

• The higher the number of different alleles for a characteristic, the greater the genetic diversity

Heterozygosity Index

The higher the proportion of heterozygotes in a population, the greater the genetic diversity

Heterozygosity index

Index of diversity formula

Units of the index of diversity formula

Niche

• the role of an organism in its environment

How many species can occupy a niche

• Niche only occupied by one species

What happens if more than one species occupy a niche?

• competition for same resources

• one species outcompetes the other

• other species use occupy new niche or extinction

Adaptations to abiotic and biotic factors

• Anatomical

• Behavioural

• Physiological

Anatomical adaptations

• observable structures of organisms - external or upon dissection - that help them survive or reproduce

Behavioural adaptations

• actions taken by organisms that help them survive or reproduce

Physiological adaptations

• features of the internal workings of organisms that help them to survive or reproduce