Life Table for Lacerta vivipara in the Netherlands[table]
Year | Number alive | Survivorship | Fecundity | Survivorship × Fecundity = Average Number of Offspring Produced per Female of Age x
0 | 1000 | 1.000 | 0.00 | 0.00 1 | 763 | 0.763 | 1.70 | 1.30 2 | 308 | 0.308 | 2.94 | 0.91 3 | 158 | 0.158 | 4.13 | 0.65 4 | 57 | 0.057 | 4.88 | 0.28 5 | 10 | 0.010 | 6.50 | 0.07 6 | 7 | 0.007 | 6.40 | 0.04 7 | 2 | 0.002 | 6.30 | 0.01
[/table]Data are from Strijbosch and Creemers, 1988.Using the life table, how would you describe the population dynamics of L. vivipara?

Question

BlackTom AI · Accepted Answer

Question restatement: Using the life table for Lacerta vivipara, determine the population dynamics of the species.
Option analysis:
- Option a: 'The population is decreasing.' At first glance, the number alive declines each year (from 1000 to 763 to 308, etc.), which might suggest a decline. However, to assess population dynamics you must consider not just yearly survivorship but lifetime reproductive output. The column 'Survivorship × Fecundity' gives the average number of offspring produced per female of age x, and when you sum these across all age classes, you obtain the net reproductive rate.
- Option b: 'The table does not provide this information.' This is inaccurate because the table provides both survivorship (l_x) and fecundity (m_x), and the product l_x m_x yields the lifetime reproductive output per female. From these data you can infer population growth or decline.
- Option c: 'The population is increasing.' This is supported by calculating the lifetime reproductive output. Compute R0 = sum over all ages of l_x m_x. Using the values given: 0.00, 1.30, 0.91, 0.65, 0.28, 0.07, 0.04, 0.01 sum to approximately 3.26. Since R0 > 1, each female, on average, leaves about 3.26 daughters that survive to reproduce, implying the population would grow over the long term (assuming constants such as density independence and stable age structure).
- Option d: 'The population is stable.' This would require R0 ≈ 1 or a precise balance between births and deaths across ages. With R0 ≈ 3.26, stability is not supported by the data; the population would not be expected to remain constant.
Additional nuance: Although the number alive declines steeply across years, the total lifetime reproduction is greater than replacement, which drives population growth rather than decline. The transient drop in numbers alive in early years does not contradict a growing population if lifetime fecundity is high enough and there are no strong density-dependent effects eroding survival or fecundity.
In summary, while observed counts of individuals decrease with age, the cumulative reproductive output per female indicates an increasing population rather than a decreasing or stable one, and the option stating the population is increasing best aligns with the life-table data. The other options misinterpret either the meaning of the table, fail to consider lifetime reproduction, or contradict the calculated net reproductive rate.

BIO 112-004 - Spring 2025: Biological Concepts and Methods I I (Lecture)

查看解析

登录即可查看完整答案

类似问题

Every year you travel to the Kalahari Desert in Botswana to study meerkats (Suricata suricatta), a small carnivore belonging to the mongoose family. As you survey the various populations of meerkats and analyze the data, you realize that population growth is most influenced by the…

The formula, r = (b – d) + (i – e), demonstrates that an increase in population size can be attributed to an increase in…

What were the ecological consequences of the rinderpest parasite for wildebeests and buffalo in the African Savannah? Choose 2 answers.

The figure above shows the growth and decline of the reindeer population on St. Paul Island. What is the main cause of the decline of the reindeer population?

Assuming that these populations are density dependent, what would be the likely outcome if the system depicted in the previous figure were allowed to continue?

You have been studying a very small population of Tasmanian Devils. What uncertainties about this small population should be of extreme importance and interest to you when prioritizing your research? (You may choose one or more answers.)

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单