Question

vanishing insects: why does biodiversity matter? although they must often seem abundant to us, insect populations globally are in trouble. more than 40% of insect species are declining and a third are endangered. just as concerning as this loss of diversity is the loss of insect biomass, which is falling by an estimated 2.5% a year. the cascading effect of insect loss threatens food chains globally. the causes are many and cumulative and include climate change, use of pesticides, and habitat loss. a pair of blue tits may collect 100 insects a day to feed one chick. the winter moth caterpillar is an invasive species in the us but provides abundant food for birds. the larvae of green lacewings feed on aphids and other soft - bodied insect pests. five crucial insect roles insects have a central role in the ecosystem services humans rely on for survival. the decline in the numbers and diversity of insects has serious consequences for a sustainable future. what may happen without insects: 1: providers insects are part of almost all food chains as prey for a wide range of other animals, including birds, bats, amphibians, and fish. recent declines in many bird populations have been linked to scarcity of insect prey. species at higher trophic levels may decline in numbers and diversity. 2: pest controllers predatory insects play a critical role in controlling the pest insects that threaten crops. they help to reduce pest control costs and increase yields, saving billions of dollars every year. pests may increase, damaging crops and forests, and pesticide use may increase. 2. (a) describe the primary cause of the current lack of genetic diversity in modern sea otter populations: (b) describe the likely reason for the low genetic diversity in the california population: (c) how might this be related to more recent declines in the california population?

Explanation:

Step1: Answer part (a)

Historically, sea - otters were heavily hunted. This led to a severe reduction in their population size, known as a bottleneck effect. A bottleneck reduces the genetic variation in a population because only a small subset of the original gene pool survives. So, the primary cause of the current lack of genetic diversity in modern sea otter populations is the historical over - hunting which caused a bottleneck effect.

Step2: Answer part (b)

The California sea otter population likely has low genetic diversity for the same reason as the overall sea otter population. The historical bottleneck due to over - hunting in the past has left the California population with limited genetic variation. Also, if the California population was a part of the overall population that went through the bottleneck, it would inherit the reduced genetic diversity.

Step3: Answer part (c)

Low genetic diversity can make a population more vulnerable to environmental changes and diseases. With limited genetic variation, there may be a lack of individuals with traits that can help the population adapt to new threats such as changes in food availability, pollution, or the introduction of new pathogens. So, the recent declines in the California population could be related to its low genetic diversity as it may not be able to adapt quickly enough to changing environmental conditions.

Answer:

(a) Historical over - hunting causing a bottleneck effect.
(b) Inheritance of reduced genetic variation from the overall population that went through a bottleneck due to over - hunting.
(c) Low genetic diversity limits the population's ability to adapt to changing environmental conditions such as food availability, pollution, or new pathogens, leading to recent declines.