Blog
November 13, 2018
Biotic homogenization: a few winners replacing many losers in the next mass extinction
Blog author: Alex Shupinski
Authors:
Michael L. McKinney – University of Tennessee, Knoxville
I have many research interests, generally focused on biological issues. I started out in paleobiology, in which I still have an active interest. In this area, I have published several papers on extinction and evolution. However, in recent years I have published increasing numbers of articles on topics relating to modern biodiversity problems and solutions, such as the effects of urbanization on biodiversity, and especially how human activities are homogenizing the biosphere. My field work is focused on land snails and mussels with a special interest in their conservation.
Julie L. Lockwood – Rutgers University, New Brunswick, New Jersey
-Studies the influx of non-native species into native ecosystems
OUR GROUP DOCUMENTS AND EXPLORES THIS TRANSITION IN BIODIVERSITY USING A VARIETY OF INTER-DISCIPLINARY RESEARCH TECHNIQUES, SEEKING TO APPLY OUR INSIGHTS TO THE TASK OF CONSERVING AND SUSTAINABLY MANAGING VALUABLE ECOSYSTEMS.
Introduction:
-Biodiversity is in decline
-Homogenization is the result of endemic species and local communities being replaces by communities of non-indigenous species. These species are typically more widespread and it ends up reducing spatial diversity.
-Past mass extinctions show biotas of lower diversity as long term disturbances encourage the distribution expansion of “winners” and the reduction or extinction for “losers”. This is being seen today when the disturbance is human activity.
How many losers and winners?
-Suggested that over 50% of species are impacted by humans and the “losers” are listed on the threatened list. If they species struggling would go extinct, the extinction rates would be level with past mass extinctions.
-Successful species include; 2% birds, 1% mammals, 2% plants (invasive weeds)
-In a local community only 5-29% of species are considered winners. But the percentage of winners gets smaller with greater levels of disturbance. And certain types of disturbance are more jeopardizing to species.
Taxonomic and ecological enhancement of homogenization
-Large scale homogenization can be enhanced by non-random selection in ecological and taxonomical groups
-Species extinction is nonrandom higher taxa, which can enhance the loss of biodiversity through selectivity. Higher taxa have traits that make them more susceptible like lower fecundity and larger size. Fewer winning species are in the higher taxa.
-Species rich taxa have an advantage and greater abundance of exotic species. Clustering of “winning” species in a family. For example, invaders of croplands are mainly herbaceous plants that grow quickly.
-Clustering of winners can also be related to transportation to new sites by certain animals that feed on them, for instance, birds carrying seeds. Also human transport.
-These winning traits tend to be concentrated and not evenly spread across species.
-The pattern of generalists and opportunistic species thriving during extinctions is a common pattern and can be seen happening today. This ultimately creates greater homogenization of species.
-The replacement of more complex functioning ecosystems to much more simpler ones.
Conclusions and future prospects
-It appears we are heading into another mass extinction with 50% or more going extinct buy only 5-29% are expanding ranges and 1-2% of the invasive species. Note, domestication of animals plays a minor role.
-Homogenization occurs and clustering of winners and losers continue in specific taxonomic groups
-They believe that this extinction will pass the extremity of any others due to human movement of species and it will result in global homogenization.
Thoughts:
I enjoyed this paper and chose this paper for the reason that it relates the traits and mass extinction patterns talked about in Jablonskis paper to the patterns we are seeing today as we witness the development of the sixth mass extinction. When they consider the percentage of species going extinct and the comparison to past mass extinctions, are they also including Pleistocene extinctions? I’m not quite sure I believe this extinction will have the ability to surpass the end-Permian extinction due to our reliability on much of them.
I found it interesting that they believe the degree of homogenization after this sixth mass extinction will be greater than that after any of the other mass extinctions. It is true that humans move foreign organisms all over the globe. However, I feel like the number of "disaster taxa" is probably similar, and surely they were quite mobile in the past. ...?
ReplyDeleteI think it is interesting the effect of the non-random phylogenetic and ecological distribution of winners and losers. I haven't seen many papers or discussions on this, but it seems important as it will further enhance homogenization and loss of ecosystem functions.
ReplyDeleteAlso, I wander if there were also winners from the Pleistocene anthropogenic disturbances, and if so, which species (besides dogs).
This review touches multiple Interesting points that I agree. Using the vocabularies "loser and winner" is little extreme to me but it makes the point. In my opinion, it is more important to distinguish these causes between the natural and non-natural homogenization on the current local and global biotic assemble. I feel that there are more people focus on the economic temporary advances which are unsustainable and mostly favors the small group of the population. This has to stop. It might be a very controversial issue but I also feel that this problem will not be solved if we keeping the politics mixed with religion. Humanity has very little time left to come up with at least a better solution on our mindset towards nature, and applicable technological innovations that are little friendly on the natural bio-systems.
ReplyDeleteI do think the author has a point about winners accelerating extinction rates. Whether the winners are invaders or local species that have a broader adaptation range, select species coming out on top lowers the overall gene pool of a population or community. Eventually this can create a positive feedback loop, with most remaining species being less able to adapt as the gene pool lowers and lowers.
ReplyDeleteThis paper adds a lot to the classic paper. The idea that the next extinction being the most extreme one because of human movement is super interesting! It does make sense to me, but I don't know enough about previous extinctions. This paper makes me question human impact on the next extinction. Introducing a new species to a habitat can also be beneficial, but it can also bring the next extinction closer..?
ReplyDeleteThe language in this paper was strange to me- talking about winners and “successful” introductions of invasive species like humans consciously did this to place bets on survival.
ReplyDeleteAdditionally, it seemed a bit obvious that the winners in a major environmental disturbance would be r-selected species. Table 3 just kind of laid out everything you expect for r vs k selected species and added how they interact with people. R-selected do best in unstable environments, so why wouldn’t they prevail here?
It ways interesting, however that they posited that humans are ramping up this process and that biomes will be even more homogeneous than before.
I found interesting how at the introduction the authors mention how invasive species might be a major cause of homogenization. He uses the examples of invasions in island, that of course have had severe effects in island's biota. However, I remember we have discussed before that there are the much more cases of species introductions that do not become invasive nor abundant, so I don't really think we could address species invasions as a major cause of homogenization. But I don't find interesting the argument about how species capable of tolerating humans invasions might more likely survive.
ReplyDeleteI'm kinda like willow where I think its interesting that words like winner and loser. I loved this paper way more than the paper I wrote my blog about because it talks about humanity and its possible impact which is something I really love to read about.
ReplyDeleteI'm with Angel, I think papers discussing humanity's impact are pretty interesting. Table 3's synopsis is pretty neat- traits that are beneficial/detrimental in a human-dominated world. How accepted are these predictions from human activity? How many account for advances in technology?
ReplyDelete