Plants differ from many animals because they undergo indeterminate (continual) growth. Indeterminate growth is common in clonal plants because a single clone can continually produce new clones without undergoing sexual reproduction, even if the plant is capable of doing so.
Senescence, an inability to undergo cell division as an organism ages, also occurs in many plants and animals. However, scientists have had a difficult time establishing the occurrence of senescence in cloning plants because of their indeterminate growth patterns. Mutations in somatic cells are common during asexual growth, and these mutations lead to a decrease in sexual fitness. Scientists hypothesize that over time, as these mutations accumulate, they may contribute to senescence in clonal plants. To test this theory, scientists studied a naturally growing population of trembling aspen (Populus tremuloides) , a tree species that grows clones from its root system but is capable of sexual reproduction. To determine if trembling aspens senesce, they compared genetic data of estimated tree age with the variable of "diminishing fertility": the amount of pollen released by male aspen trees. Here are the results for this part of the study:
Source: Adapted from Ally, D., Ritland, K., & Otto, S. P. (2010) . Aging in a long-lived clonal tree. PLoS Biol, 8(8) : e1000454. doi:10.1371/journal.pbio.1000454.
-If you generalize the trends in data to 20,000 years, what can you conclude?
Definitions:
Leading Questions
Questions framed in a way that suggests a particular answer or influences the response, often used in legal settings, interviews, and surveys to shape the respondent's answer.
Cochran and Colleagues
A group of researchers known for their contributions to a specific field or study, though the context of their work would determine their specific domain of expertise.
Eyewitnesses
Individuals who have directly observed an event and can provide a first-hand account or testimony of that event.
Reliability
The degree to which an assessment tool produces stable and consistent results over time.
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