Monday, April 23, 2018
“The potential magnitude of unintentional human selection should not be underestimated.”
Authors Kathryn G. Turner, Christopher J. Schell, and Brook T. Moyers report in their recent article “Genomics of Adaptation to Human Contexts” (Journal of Heredity, 2018, Vol. 109, No. 2) the summaries of a one day symposium of geneticists and their published papers. One key paragraph of their article states:
“Moyers et al. (this issue) review the evidence for a genetic “cost of domestication,” and that with few exceptions, domesticated lineages show signs of increased deleterious genetic variation compared to their wild relatives. These signs include increased genome-wide linkage disequilibrium, reduced genetic diversity, increased numbers or substitutions of nonsynonymous relative to synonymous mutations, and more numerous or frequent mutations that annotate as deleterious in comparative analyses. The same pattern is found when comparing modern domesticated lineages subject to recent intense artificial selection (elite or improved varieties) against older domesticated lineages (landrace or noncommercial varieties). These patterns are likely driven by the combination of repeated genetic bottlenecks, strong artificial selection, and increased inbreeding that humans have intentionally and unintentionally applied during the process of domestication.”
Monday, April 16, 2018
It may be useful to evaluate surrounding green spaces and their connectivity when creating urban wildlife habitat. A study done in Syracuse, NY in 1986 found that many mammal species don't just stay within one habitat type, but instead use a mosaic of spaces for varying needs. The researchers found that by studying the variables found within a regional area were more important than site specific landscapes. The area of water, amount of paving, grass area, and green space amounts were more important than classes of trees or amount of understory. The authors conclude that urban animals use a regional approach for habitat needs than individual site provisions.
Tuesday, April 10, 2018
Good ag neighbors: Rare remnant plant species are better conserved in larger forest patches next to ag lands than urban
Because of publisher copyright restrictions I can't share the research abstract, however I can summarize an interesting study in 2006 that found that agricultural lands are better neighbors than urban land use that adjoin remnant woodlots. The study that was done in Spain found that plant species recorded were compared to levels of human disturbance and frequency. Results were determined that disturbance-type plant species decreased with increasing distance to forest edge. Rare forest species were richer in large patches adjacent ag-based lands as compared to small woodland patches in peri-urban areas.
Tuesday, April 3, 2018
“Plants are really the thermostat of the world,” says Léo Lemordant, Gentine’s PhD student and lead author of the paper. “They’re at the center of the water, energy, and carbon cycles. As they take up carbon from the atmosphere to thrive, they release water that they take from the soils. Doing that, they also cool off the surface, controlling the temperature that we all feel. Now we know that mainly plants—not simply precipitation or temperature—will tell us whether we will live in a drier or wetter world.”
Their study“Critical impact of vegetation physiology on the continental hydrologic cycle in response to increasing CO2.”is published in Proceedings of the National Academy of Sciences. Authors are: Léo Lemordant (Columbia Engineering); Pierre Gentine (Columbia Engineering and Earth Institute); Abigail Swann (University of Washington); Benjamin I. Cook (NASA Goddard Institute for Space Studies and Lamont-Doherty Earth Observatory, Columbia University); and Jacob Scheff (University of North Carolina, Charlotte).
Wednesday, March 28, 2018
"We show that urban growth of any type reduces bird distributions overall, but compact development substantially slows these reductions at the city scale."
Sushinsky et al evaluated the changes in bird populations between sprawling cities and dense, compact cities. They found that while all urban growth reduces overall bird density but that compact cities have slower declines. In their 2012 Global Change Biology journal article that "Our results suggest that cities built to minimize per capita ecological impact are characterized by high residential density, with large interstitial green spaces and small backyards, and that there are important trade‐offs between maintaining city‐wide species diversity and people's access to biodiversity in their own backyard."
Monday, March 12, 2018
Urban and Roehm's research on studying temporary wetlands and associated species was published in the January 2018 Oecologia. It observesthat exurban ponds tend to be designed and managed as permanent waterbodies which retain permanent wetland species but fewer temporary wetland types.
Swamp Forest Exhibit at Crosby Arboretum was designed as a temporary stream corridor
"Exurban areas are expanding throughout the world, yet their effects on local biodiversity remain poorly understood. Wetlands, in particular, face ongoing and substantial threats from exurban development. We predicted that exurbanization would reduce the diversity of wetland amphibian and invertebrate communities and that more spatially aggregated residential development would leave more undisturbed natural land, thereby promoting greater local diversity. Using structural equation models, we tested a series of predictions about the direct and indirect pathways by which exurbanization extent, spatial pattern, and wetland characteristics might affect diversity patterns in 38 wetlands recorded during a growing season. We used redundancy, indicator species, and nested community analyses to evaluate how exurbanization affected species composition. In contrast to expectations, we found higher diversity in exurban wetlands. We also found that housing aggregation did not significantly affect diversity. Exurbanization affected biodiversity indirectly by increasing roads and development, which promoted permanent wetlands with less canopy cover and more aquatic vegetation. These pond characteristics supported greater diversity. However, exurbanization was associated with fewer temporary wetlands and fewer of the species that depend on these habitats. Moreover, the best indicator species for an exurban wetland was the ram’s head snail, a common disease vector in disturbed ponds. Overall, results suggest that exurbanization is homogenizing wetlands into more permanent water bodies. These more permanent, exurban ponds support higher overall animal diversity, but exclude temporary wetland specialists. Conserving the full assemblage of wetland species in expanding exurban regions throughout the world will require protecting and creating temporary wetlands."
Abstract cited from: Urban, M.C. & Roehm, R. Oecologia (2018) 186: 291. https://doi.org/10.1007/s00442-017-3989-y
Friday, March 9, 2018
“In a study published today in Proceedings of the National Academy of Sciences, a team led by atmospheric scientists Logan Mitchell and John Lin report that suburban sprawl increases CO2 emissions more than similar population growth in a developed urban core.
“The general thought is that more compact cities on a per capita basis emits less carbon,” Lin says. “Some of these cities also have these expanding fringes. These places are less ‘green’, so to speak. That expanding frontier is moving.””
Published in https://unews.utah.edu/u-co2-sensor-network/