Biology Unit 2 Topic 4

Biodiversity and Natural Resources

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  • Created by: Connor
  • Created on: 24-05-11 13:10

Biodiversity

Definition: measure of a variety of living organisms and their genetic differences. The differences between certain organisms and a species, between populations of the same type, between communities and ecosystems. Every form of life have specific characteristics depending on their genes. It is important because all organisms are interdependent so they can affect each other’s survival. If the biodiversity is reduced in one area, the natural balance may be destroyed in another area. It has allowed us to develop the production of crops, livestock, fisheries and forests. Further improvements can be made to cross-breeding and genetic engineering.  

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Species

Definition: as a group of closely related organisms that are able to produce fertile offspring. We can look at the morphology (appearance) and the molecular phylogeny (genetic make-up)

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Binomial Nomenclature

First name is genus (capital letter) Second name is species Both in italic   e.g. Homo sapiens

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Molecular Phylogeny and the 3 domains

Biochemical analysis can either support or conflict with relationships based on morphology. E.g. American porcupines and African porcupines occupy similar niches but have their biochemical analysis suggests that they’re only distantly related. Many years it has been thought that there are 2 domains – prokaryotes and eukaryotes, this theory was that eukaryotes were developed from prokaryotes. However, now another domain is recognised, the Archaea. The 3 domains are now known as Bacteria, Archaea and Eukaryota. Genetics show that the 3 domains probably had a single common ancestor 3 billion year ago. Archaea and Eukaryota are thought to share a more recent common ancestor with each other than Bacteria.

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Ecology and Adaptation

Definition: the study of relationships between living organisms and their environment. The Niche Concept An organism’s niche is particular role in an ecosystem. This includes; -It’s habitat (spatial) -Feeding behaviour (keeping other populations in check) -Interactions with other species The interactions are competition, herbivory, predation, parasitism, mutualism.  

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Competitive Exclusion

Two species in a community can occupy the same niche and so they compete for the same resources; one will die and one will survive because one is better adapted. Also, known as natural selection.

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Adaptations to Niches

A successful species is adapted to it’s role in the community which means it has characteristics that help them survive and reproduce. Three types are; Anatomical Physiological Behavioural

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Anatomical

Related to it’s structure. e.g. Seals have a thick layer of blubber that keeps them warm and also has buoyancy which acts to streamline the body because they are aquatic animals.

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Physiological

The functioning of the organism at levels from biochemical, to cellular, tissue, organ and whole organism levels. Marmots go into a state of estivation to survive extreme temperatures of the desert. This is a dormant state where breathing, heartbeat and other body processes slow down, which reduces the need for water.

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Behavioural

The way an organism acts to increase it’s chance of survival and reproduction. Swiftlets use audible sounds to echolocate in the darkness of caves. Mosses and ferns grow atop other plants to reach the sunlight in temperate forests.

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Ecology Key Terms

Ecosystem: a community and its abiotic environment. Habitat: the environment in which a species lives or the location of a living organism. Population: a group of organisms of the same species who live in the same area at same time. Community: a group of populations living and interacting with each other in an area. Consumer: an organism that ingests other organic matter that is living or recently killed.

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Continued...

Autotroph: an organism that synthesises it’s organic molecules from simple inorganic substances. Heterotroph: an organism that obtains organic molecules from other organisms. Detritivore: an organism that ingests non-living organic matter. Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion.

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Natural Selection and Evolution

Variation Lots of offspring Competition for resources available (light, food, water, habitat). Individuals not well adapted may not survive to reproduce and vice versa. Offspring that have alleles which benefit them the most.

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Mutations

Can cause small changes in the genes.

Size of the gene pool increases. Changes in physical appearance, physiology, and the behaviour. Advantageous alleles increase, disadvantageous will be removed by natural selection. Sometimes they are neutral and will remain in the gene pool.

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Continued

Three types of selection:

  • Directional – environmental pressure applied to population will see to the phenotype changing.
  • Diversifying – diversity increase which can lead to 2 new populations if the pressure is strong.
  • Balancing – variety is maintained by keeping an allele within the population.
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Conservation: In situ

In situ Protects species in their own habitat. Benefits – already adapted, and species can continue this process without outside influence. Risks – difficult to protect from the threats like humans, expensive, resources and research needed.

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Conservation: Ex situ

Ex situ Last resort if organisms can’t be kept safe. Methods – captive breeding, artificial insemination, embryo transfer and pedigrees are kept to prevent inbreeding. Botanical Gardens – easy method of breeding plants. Seed Banks – allow them to be kept for decades.

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Adapting to Change

Small Populations   Large populations who have large gene pools have less chance of losing an allele. So the smaller it is you lose genetic diversity   The Founder Effect   When a small no. of individuals leave a population and set up a new one the genetic diversity can be lost therefore the frequency of alleles decreases. Unusual genes in the founder members may be amplified as the population grows.

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Isolating Mechanisms

In order for different species to evolve from the original one, populations have to be isolated. Ways are: -Geographical- physical barrier -Ecological- 2 pptns inhabit same region but have preferences for parts of the habitats -Seasonal- breeding seasons don’t overlap -Behavioural- differing courtship rituals, mating patterns so animals don’t recognise others as potential mates -Mechanical- changes in relationships

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Speciation

  • Allopatric- groups are physically separated e.g. Geographical, seasonal, ecological
  • Sympatric- 2 populations close e.g. Mechanical, seasonal, behavioural
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Endemism

Describes how species are found in one area, said to be endemic to the region. Due to evolution within a region, without migration. Islands have endemic species. Low genetic diversity because species have been split off.

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Biodiversity II

Keystone Species Certain species have an important impact on the environment, a large no. of  different species will depend on it’s presence. e.g. Sea otters and kelp forests

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Measuring Diversity

  • Evenness (abundance of species in comparison to others)

Communities aren’t considered to be diverse if dominated by one species Richness (number of different species)

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Indicator Species

Some are sensitive to environmental change. Common indicators are: -Lichens for air pollution -Macroinvertebrates in rivers

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How to analyse genetic biodiversity

Analyse the DNA to build a clear model of genetic diversity within a pptn. Maps are generated to highlight areas of high diversity and in need of protection. Extinction: Permanent loss of all members in a species, before this happens pptn size and genetic diversity decreases. Habitat destruction, pollution, hunting and foraging, alien species introduction, climate change?

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Hotspots

Contain unusual biodiversity and endemism. Make up 15.7% of Earth’s land surface. Wet tropics are areas of high biodiversity. Theories: -High levels of productivity (photosynthesis) can support more niches -More mutations happen when organisms grow and reproduce rapidly which increases variety enabling them to adapt to particular niches and evolve into new species.

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