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MAKING SENSE OF STAGE 1 BIOLOGY SEM 2 (BIODIVERSITY: biodiversity is the…
MAKING SENSE OF STAGE 1 BIOLOGY SEM 2
BIODIVERSITY: biodiversity is the variety of all living things and includes diversity in genetics, species and ecosystems.
Distinguish between a species, population, community, and an ecosystem.
SPECIES: a group of closely related organisms that, in nature, are capable of mating and producing viable, fertile offspring that are also reproductively isolated by either biological or physical barriers
POPULATION: organisms of a particular species live together in populations, a group of organisms of one species that interbreed and live in the same place at the same time
COMMUNITY: a community is an ecological grouping of different species that live together in a particular place at a particular time, and interact with one another
ECOSYSTEM: the system formed by a community of diverse living organisms interacting with one another in a particular place at a particular time, together with their physical surroundings
EVOLUTION:the cumulative change in the heritable characteristics of a population driven by genetic variation (random) and natural selection (differentially selective)
MICROEVOLUTION:-microevolution describes evolutionary changes that occur over a relatively short period of geologic time (such as between generations)
-results in diversification within a species
MUTATION:a random change in the genetic composition of an organism due to changes in the DNA base sequence
RANDOM MATING:sex can introduce new gene combinations into a population
GENE FLOW: the movement of alleles into, or out of, a population as a result of immigration and emigration (also called gene migration)
GENETIC DRIFT: -the change in the composition of a gene pool as a result of a random or chance event
-occurs faster and is more significant in small populations, where chance events have a bigger impact on the gene pool
FOUNDER EFFECT:
when a small group breaks away from a larger population to colonise new territory
this population subset does not have the genetic diversity of the main population, subject to a higher level of genetic drift
as the small population increases in numbers the new population will no longer be representative of the original gene pool
BOTTLENECK EFFECT:
when natural disasters or events like forest fires or man-made events like deforestation reduce a population size by more than 50%
surviving population contains less genetic variability - smaller gene pool
as surviving members repopulate the new population will no longer represent the original gene pool
MACROEVOLUTION: evolutionary relationships that occur over a relatively long period of geologic time, results in diversification between species
cell -> human
WHAT DOES A LARGE GENE POOL INDICATE? a large gene pool indicates high amounts of genetic diversity, increasing the chances of biological fitness and survival
WHAT DOES A SMALL GENE POOL INDICATE? a small gene pool indicates low amounts of genetic diversity, reducing biological fitness and increasing chances of extinction
Other key terms.
ABIOTIC FACTOR: abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems
BIOTIC FACTORS: biotic factors are living parts of the ecosystem with which an organism must interact
TWO MAIN COMPONENTS OF BIODIVERSITY / SPECIES DIVERSITY
SPECIES RICHNESS: number of species
SPECIES EVENNESS: evenness in abundance of species
SPECIES DIVERSITY: species diversity is the number of species and abundance of each species (richness + evenness)
ALLELE: one of a number of different forms of a gene
GENE POOL: totality of genes (and their particular alleles) within a sexually reproducing population
ALLELE FREQUENCY: the proportion of a particular allele within a population
ECOLOGICAL NICHE:a specific role of a species within an ecosystem, including its use of resources, and relationships with other species
NICHE DIAGRAMS
IMPACTS OF COMPETITION? competition can effect species niche either by narrowing the optimum niche or changing the niche area entirely - the organism needs to adapt to a new/different environment.
GENERALISTS:generalist species has a very broad range of resources they can use
SPECIALISTS: specialists have a very narrow niche - if the resource gets destroyed, they've lost their niche
CLASSIFICATION
TAXA
domain
kingdom
phylum
class
order
family
genus
species
king penguins climb over frozen grassy slopes
BINOMIAL SYSTEM OF NOMENCLATURE
capital genus, no capital species
DICHOTOMOUS KEYS:
a method of identification whereby groups of organisms are divided into two categories repeatedly
with each sequential division, more information is revealed about the specific features of a particular organism
when the organism no longer shares its totality of selected characteristics with any organism, it has been identified
REPRODUCTIVE ISOLATION
PREZYGOTIC: occurs before fertilisation can occur (no offspring are produced)
temporal, behavioural & geographic isolation
POSTZYGOTIC: occurs after fertilisation (offspring are either not viable or infertile)
ADAPTATION:mutation or genetic change that helps an organism survive, therefore it is passed down from one generation to the next
physiological
behavioural
structural
KEY STONE SPECIES An organism that plays and unique and crucial role in the functioning of an ecosystem, without the species, the ecosystem would be drastically different or seize to exist all together.
PREDATORS: Exert pressure on lower trophic levels to help prevent them from monpolising certain resources.
MUTUALISTS: Support the lifecycles of a variety of species within the community (pollinators / seed dispersal)
ENGINEERS: Refashion the environment to aid the survival of other organisms.
SUCCESSION The gradual process by which ecosystems change and develop over time.
PRIMARY SUCCESSION: occurs in an environment which is devoid of vegetation, other organisms and usually soil, due to factors such as a lava flow
species such as lichen or moss grow, these species then die and decompose forming the first soil, this then makes way for fast growing plants
SECONDARY SUCCESSION: occurs in areas where a community that previously existed has been removed; typified by smaller scale disturbances that do not eliminate all life and nutrients from the environment
after the moderate natural environmental disturbance, bare soil usually remains and fast growing plants repopulate the area
SELECTION PRESSURES external agents which impact an organism's ability to survive in a given environment, can be positive or negative (increase or decrease the proportion of a trait), they're always changing
DENSITY DEPENDENT
PANDA
Predators
Availability of resources (Shelter + water)
Nutrient availability
Disease / pathogenic spread
Accumulation of wastes
DENSITY INDEPENDENT
PAW
Phenomena (natural disasters)
Abiotic factors (co2 levels & temperature)
Weather conditions (floods)
FOSSILS PROVIDE EVIDENCE FOR CHANGES THAT HAVE OCCURRED IN THE FEATURES OF ORGANISMS ON THE PLANET (EVOLUTION)
COMPETITIVE EXCLUSION