A4 - Ecosystems Flashcards
(45 cards)
What is evolution?
Evolution is the change in the heritable characteristics of a population over time.
Who was Lamarck and what was his theory of evolution?
Jean-Baptiste Lamarck proposed a theory of evolution in the early 19th century that involved use and disuse of structures. Frequently used structures would strengthen and enlarge; non-used structures would weaken and deteriorate.
What is the inheritance of acquired characteristics?
According to Lamarck, physical changes to structures (from use/disuse) during an organism’s lifetime are inherited by offspring.
What was Darwin’s theory of evolution?
Darwin proposed evolution by natural selection. Heritable variations that benefit survival and reproduction are passed to offspring, increasing their frequency over generations in the population.
What is a paradigm shift in biology?
A paradigm shift is a fundamental change in scientific understanding — e.g., the shift from Lamarckism to Darwinian natural selection.
Define mutations, state what it changes and what it can change, and what acts on it if adaptive . How can this be tracked ?
- Mutations are random alterations in the genetic code (e.g. DNA replication errors).
- Mutations change DNA base sequences → can change amino acid sequences in proteins.
- Natural selection acts on adaptive mutations (not harmful ones).
- Evolution can be tracked by sequencing DNA, RNA, or amino acid sequences over time.
What does sequence similarity indicate about relatedness?
The more similar the sequences, the more closely related the organisms are.
What is divergence and how does it support evolution?
Divergence is the accumulation of mutations over time in DNA sequences → leads to changes in proteins. These differences can be used to build evolutionary trees.
What is comparative genomics?
Comparative genomics compares genomes of different organisms to identify conserved regions shared from common ancestry.
What is cladistics analysis?
By aligning and comparing genetic sequences across multiple species, scientists can construct cladograms to visually represent evolutionary relationships.
What is selective breeding?
Selective breeding is when humans choose organisms with desirable characteristics and breed them repeatedly → increases expression of that trait over generations.
Why is selective breeding evidence for evolution?
Because it shows a change in the frequency of characteristics over generations, caused by human selection → e.g., artificial selection.
What is the process of selective breeding?
- Variation exists in population. 2. Breeders select individuals with desired trait. 3. These individuals are bred together. 4. Offspring are tested and the best are bred again. 5. Process repeats over generations → frequency of trait increases.
Examples of evolution through selective breeding?
• Teosinte → Corn • Brassica diversification (cabbage, kale, broccoli, etc.)
What is divergent evolution?
Divergent evolution is when species of common ancestry evolve different traits due to different selection pressures → leads to speciation.
What are homologous structures?
Homologous structures are similar in form and structure due to inheritance from a common ancestor, but may differ in function.
What is the pentadactyl limb and why is it an example of homologous structure?
A pentadactyl limb has 5 digits. Present in mammals, reptiles, birds, amphibians. Despite different functions (walking, flying, swimming), the underlying bone structure is similar → shows common ancestry.
What is anthropogenic extinction?
Extinction caused by human activities.
Case study: North Island Giant Moas
• Flightless, herbivorous bird in New Zealand • Humans arrived ~1200–1300 CE • Hunted to extinction by ~1445
Case study: Caribbean Monk Seals
• Lived in oceans around Gulf of Mexico & Caribbean • Hunted for oil & meat • Declared extinct in 2008
Case study: Passenger Pigeon
• Once the most abundant bird in North America • Hunted in 1800s, habitat loss from deforestation • Declared extinct by 1914
What caused the loss of the mixed dipterocarp forest?
• In Southeast Asia • Clear-cutting of trees for agriculture (e.g., palm oil) • Ecosystem loss due to deforestation
What caused the loss of the Mar Menor ecosystem?
• Located in Spain • Intensive agriculture, water extraction, pollution • Resulted in poor water quality, biodiversity loss • Impacted important species (e.g., seagrasses, marine fauna) • Flamingo feeding/nesting habitats affected
To be trustworthy, biodiversity evidence must:
• Use reliable surveys repeated over time • Assess both species richness & evenness • Be gathered by experts • Come from published, peer-reviewed sources
