A4 Unity and Diversity : Ecosystems Flashcards
Evolution, speciation and conservation
natural selection
The process in which different environments influences the survival and reproduction of organisms due to the presence of variations or adaptations.
Lamark’s theory
that characteristics which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears.
Darwin’s theory of evolution
States that variation occurred randomly among members of a species; that an individual’s traits could be inherited by its progeny; and that the struggle for existence would allow only those with favourable traits to survive.
molecular phylogeny
Comparative analysis of the nucleotide sequences of DNA and RNA and the amino acid sequences of proteins.
selective breeding
Also known as artificial selection where humans select individuals from a species to breed together based on desirable characteristics.
Homologous structures
Structures that physically similar and share a common ancestor, but perform different functions in different species.
divergent evolution
Pattern of evolution where organisms arising from the same ancestral species adapt to different environmental conditions according to the pressures of natural selection.
convergent evolution
Pattern of evolution where distantly related organisms evolve similar traits in response to environmental similarities.
population
A group of organisms of one species, living in the same area at the same time.
genetic drift
A group of organisms of one species, living in the same area at the same time.
allopatric speciation
Evolution of one or more new species from an ancestral species due to a geographical barrier.
sympatric speciation
Evolution of one or more new species from an ancestral species while living in the same geographical area.
gamete
A reproductive cell of an animal or plant.
prezygotic barriers
A form of reproductive isolation that takes place before fertilisation.
postzygotic barriers
A form of reproductive isolation that takes place after fertilisation.
adaptive radiation
Evolution of multiple new species from an ancestral species to occupy different ecological niches.
ecological niches
The position of a species within an ecosystem or community and its interrelationships with both biotic and abiotic factors.
polyploidy
A condition where an organism possesses more than two sets of chromosomes.
non-disjunctional
The failure of homologous chromosomes or sister chromatids to separate during cell division.
mitosis
Equational cell division resulting in daughter cells that are genetically identical to the parent cell.
meiosis
Cell division that produces gametes and reduces the amount of genetic information in each cell.
genetic diversity
The diversity seen in the genes (alleles) within a population of a species.
species diversity
The number and types of organisms that existed during a specific amount of time.
ecosystem diversity
Variety in ecosystems in a given area
community
A group of interacting species in a particular environment. For example, a forest – with its trees, plants, animals, bacteria and fungi.
decomposition
The process of breakdown of complex (dead) organic substances into simpler organic or inorganic substances.
keystone species
A species that plays a critical role in maintaining the structure and functioning of an ecosystem. The presence or absence of a keystone species can significantly impact the overall biodiversity and stability of the ecosystem.
epiphytic plants
Plants that grow on the surface of other plants using them only for support. For example, orchids.
polyps
A coral invertebrate with an outer hard, cup-shaped skeleton made of calcium carbonate.
multi-pronged approach
Different measures need to be taken to protect different species.
In-situ conservation
Refers to on-site conservation techniques.
ex-situ conservation
Refers to conservation of plants and animals outside their natural habitats.
EDGE species
Evolutionarily Distinct and Globally Endangered eg- Aye-aye, pangolin
