A. During each mass extinction event, there is a significant decline in the number of animal families. Typically, the number of families decreases sharply at the time of the extinction event itself, reflecting the massive loss of biodiversity. After each mass extinction, there often follows a gradual increase in the number of animal families as new species evolve and adapt to fill the ecological niches left vacant by the extinctions. However, this recovery process can take millions of years, and the overall number of families may take a significant amount of time to return to pre-extinction levels, if they do so at all.
B. If Earth is currently experiencing its sixth mass extinction, we can expect a similar pattern to previous events: a sharp decline in the number of animal families as many species face extinction due to factors like habitat loss, climate change, pollution, and overexploitation. Over the coming years to decades, the immediate aftermath may see a significant drop in biodiversity. If this trend continues, we might witness a prolonged period of low biodiversity, and it could take millions of years for ecosystems to recover fully. During this time, if recovery does happen, it may predominantly feature species that can adapt to human-altered environments, which might not resemble the previous ecological compositions. Over geological time, as new species evolve to fill the niches left behind, we could see a gradual increase in the number of animal families again, but likely this would take a substantial amount of time and may lead to a fundamentally different set of families and species than are present today.