Podcast
Questions and Answers
Which factor is primarily responsible for the current sixth biological crisis?
Which factor is primarily responsible for the current sixth biological crisis?
- Asteroid impacts
- Volcanic activity
- Major climate shifts
- Human activities (correct)
What characterizes biological crises in Earth's history?
What characterizes biological crises in Earth's history?
- Increased biodiversity and species diversification
- Massive extinctions of species across various environments (correct)
- Gradual adaptation of species to changing environments
- Localized species extinctions in specific habitats
How does genetic drift impact small, isolated populations?
How does genetic drift impact small, isolated populations?
- It has a weaker effect due to the limited number of individuals
- It can cause significant allele frequency changes from one generation to the next. (correct)
- It leads to a predictable increase in genetic diversity.
- It promotes genetic stability and reduces the risk of extinction
What is the ultimate result of genetic drift on a particular allele within a population?
What is the ultimate result of genetic drift on a particular allele within a population?
What distinguishes the sixth biological crisis from the previous five?
What distinguishes the sixth biological crisis from the previous five?
How have past biological crises influenced biodiversity on Earth?
How have past biological crises influenced biodiversity on Earth?
What is a key characteristic of the biodiversity changes observed on short timescales?
What is a key characteristic of the biodiversity changes observed on short timescales?
Which of the following scenarios exemplifies genetic drift?
Which of the following scenarios exemplifies genetic drift?
How does the introduction of the Podarsis lizard onto a small Croatian island demonstrate changes in biodiversity?
How does the introduction of the Podarsis lizard onto a small Croatian island demonstrate changes in biodiversity?
What planetary events are associated with major extinction events?
What planetary events are associated with major extinction events?
Flashcards
Biodiversity on short timescales
Biodiversity on short timescales
Changes in biodiversity observed over short periods.
Biological crises
Biological crises
Major events in Earth's history marked by significant species extinctions.
Genetic drift
Genetic drift
A random evolutionary mechanism where allele frequencies change due to chance.
Allele loss
Allele loss
Signup and view all the flashcards
Allele fixation
Allele fixation
Signup and view all the flashcards
Study Notes
- Biodiversity evolves over time, with current biodiversity representing only a small portion of the species that have existed since the beginning of life on Earth approximately 3.5 billion years ago.
Changes in Biodiversity Observable over Short Timescales
- Biodiversity constantly evolves.
- Variations in biodiversity can be observed over short timescales
- These changes occur at the genetic level, where mutations in certain genes result in new alleles that can produce new traits within a population, such as the Podarsis lizard introduced on the small Croatian island.
- Changes also occur at the species level, with various species appearing in the last 20 centuries in France
Biological Crises
- Living beings have undergone five major biological crises in Earth's history.
- These crises result in mass extinctions of species in all environments worldwide.
- Crises are followed by a rapid diversification of species.
- Major planetary events such as climate shifts, asteroid impacts, and exceptional volcanism cause these crises.
- Currently, a sixth biological crisis is happening with very high species extinction rates.
- Human activities are causing this crisis
Genetic Drift
- Another evolutionary mechanism, solely due to chance, occurs at the population level where not all individuals leave the same number of descendants.
- Allele frequency can change randomly as a result. This phenomenon is called genetic drift, and its strength relates to the magnitude of allele frequency variations from one generation to the next.
- It is stronger when original populations are small, for example when a dwindling population (sea elephants) or when a group isolates itself (Ngorongoro crater lions).
- Within a population, genetic drift can lead to the disappearance of an allele or its fixation, where all individuals possess the same allele.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
