When a population is small, the effect of genetic drift increases, leading to less allele fixation and/or random fixation. This, in essence, contributes to increased homozygosity, which affects species fitness negatively. Plant production can be affected by less efficient selection, which in small populations causes the accumulation of deleterious mutations. Since indivividuals are more likely to be linked to small groups, they are more likely to be inbred. Due to mutation accumulation, decreased genetic diversity, and increased inbreeding, a reduction in fitness may occur in small plant populations. The evolutionary ability and the capacity of a species to adapt to a changing environment, such as climate change, are diminished over time. Global warming, can lead to population fragmentation especially when coupled with mountains, reducing movement from one habitat to another
In forest areas, fragmantion can be claculated geographically and annual changes can be extracted. the situatin is differint in Scattered distribution of small herbs grow in mountain ecosystem, it is so difficult the calculate the fragmentation trend geographically (it’s not savanna or high covered forest that can calculate the yearly geographical changes), is there any method to calculate the fragmentation changes in population of such small herbs geographically?
You would need to compare aerial photographs or sampling quadrats from different time periods
Dear Andrew Paul McKenzie Pegman
Thanks for your replay
That is actually what I do " sampling quadrats from different time periods "
Aerial photographs for very small herbs (5- 10 cm ) scattered in the mountains especially between rooks are very difficult to be observed.
I used to collect data about species distribution EOO and AOO number of subpopulations so i can observe the population trend, but i think there is another options
Do a common garden study of the target plants, and the genetic differences will stand out when you grow them side-by-side at the same time under the same conditions. See my common garden study of our local native grasses, and where the different environmental extremes created fixed genetic ecotypes, that were very clearly seen in the common garden.
The common garden photos were plant populations in the local mountains taken from a small area, only a 40 x 40 kilometer area, and the Marin County chert and the Marin County serpentine were only 100 meters apart on different soil types. https://www.ecoseeds.com/juicy.gossip.three.html
Also, be aware of what created the local ecotypes in the first place... may be more plastic than you realize, in that what morphed those ecotype populations into the places they exist today, can modify the genetics to adapt to changing global warming or other conditions also.
You can see this evolution occurring in real-time when you look at the populations that are at the extreme edges of where the species is growing--the extreme low rainfall edge, the extreme elevation edge, the radically different soil types, the extreme north and south boundaries of the populations--this is where you can view evolution in real-time.
Mountain ecosystems are geographically very unique and the changes in plant populations of such ecosystems are need to be carefully monitored. In the scenario of climate change and global warming, genetic diversity is much essential to adapt the plant populations to the changing conditions.Remote sensing ( aerial photography)is one of the useful method to assess the fragmentation of plant population in mountain ecosystems.
Dear Pasupuleti Sivaramakrishna
Thanks for your replay. Aerial photographs for very small herbs (5- 10 cm ) scattered in the mountains especially between rooks are very difficult to be observed.
I used to collect data about species distribution EOO and AOO number of subpopulations so i can observe the population trend, but i think there is another options
Dear Karim Omar
As you said, quadrats or other sampling methods, such as transects, at the same points in different places and at different times, but in short periods (because these herbs tend to have short reproductive cycles and are annual) can be a way of doing this monitoring. But, I think that in addition to the population size, the flow between populations and other reproductive parameters should be monitored.
Isolated plant populations that are wind or insect pollinated wild species, can only transfer genes it they are close enough to do so. However they could be at the edge of environmental extremes, and then "fix" their genetic material to be able to live in that different environmental habitat. That is why planting a common garden, and see what are the fixed difference are, is so important.
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