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Do American Dippers Obtain a Survival Benefit from Altitudinal Migration?

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2015
Abstract: 

Studies of partial migrants provide an opportunity to assess the cost and benefits of migration. Previous work has demonstrated that sedentary American dippers (residents) have higher annual productivity than altitudinal migrants that move to higher elevations to breed. Here we use a ten-year (30 period) mark-recapture dataset to evaluate whether migrants offset their lower productivity with higher survival during the migration-breeding period when they occupy different habitat, or early and late-winter periods when they coexist with residents. Mark-recapture models provide no evidence that apparent monthly survival of migrants is higher than that of residents at any time of the year. The best-supported model suggests that monthly survival is higher in the migration-breeding period than winter periods. Another well-supported model suggested that residency conferred a survival benefit, and annual apparent survival (calculated from model weighted monthly apparent survival estimates using the Delta method) of residents (0.511 ± 0.038SE) was slightly higher than that of migrants (0.487 ± 0.032). Winter survival of American dippers was influenced by environmental conditions; monthly apparent survival increased as maximum daily flow rates increased and declined as winter temperatures became colder. However, we found no evidence that environmental conditions altered differences in winter survival of residents and migrants. Since migratory American dippers have lower productivity and slightly lower survival than residents our data suggests that partial migration is likely an outcome of competition for limited nest sites at low elevations, with less competitive individuals being forced to migrate to higher elevations in order to breed.

Document type: 
Article
File(s): 

Effects of Salmon-Derived Nutrients and Habitat Characteristics on Population Densities of Stream-Resident Sculpins

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2015
Abstract: 

Movement of nutrients across ecosystem boundaries can have important effects on food webs and population dynamics. An example from the North Pacific Rim is the connection between productive marine ecosystems and freshwaters driven by annual spawning migrations of Pacific salmon (Oncorhynchus spp). While a growing body of research has highlighted the importance of both pulsed nutrient subsidies and disturbance by spawning salmon, their effects on population densities of vertebrate consumers have rarely been tested, especially across streams spanning a wide range of natural variation in salmon densities and habitat characteristics. We studied resident freshwater prickly (Cottus asper), and coastrange sculpins (C. aleuticus) in coastal salmon spawning streams to test whether their population densities are affected by spawning densities of pink and chum salmon (O. gorbuscha and O. keta), as well as habitat characteristics. Coastrange sculpins occurred in the highest densities in streams with high densities of spawning pink and chum salmon. They also were more dense in streams with high pH, large watersheds, less area covered by pools, and lower gradients. In contrast, prickly sculpin densities were higher in streams with more large wood and pools, and less canopy cover, but their densities were not correlated with salmon. These results for coastrange sculpins provide evidence of a numerical population response by freshwater fish to increased availability of salmon subsidies in streams. These results demonstrate complex and context-dependent relationships between spawning Pacific salmon and coastal ecosystems and can inform an ecosystem-based approach to their management and conservation.

Document type: 
Article
File(s): 

Poecilia picta, a Close Relative to the Guppy, Exhibits Red Male Coloration Polymorphism: A System for Phylogenetic Comparisons

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2015
Abstract: 

Studies on the evolution of female preference and male color polymorphism frequently focus on single species since traits and preferences are thought to co-evolve. The guppy, Poecilia reticulata, has long been a premier model for such studies because female preferences and orange coloration are well known to covary, especially in upstream/downstream pairs of populations. However, focused single species studies lack the explanatory power of the comparative method, which requires detailed knowledge of multiple species with known evolutionary relationships. Here we describe a red color polymorphism in Poecilia picta, a close relative to guppies. We show that this polymorphism is restricted to males and is maintained in natural populations of mainland South America. Using tests of female preference we show female P. picta are not more attracted to red males, despite preferences for red/orange in closely related species, such as P. reticulata and P. parae. Male color patterns in these closely related species are different from P. picta in that they occur in discrete patches and are frequently Y chromosome-linked. P. reticulata have an almost infinite number of male patterns, while P. parae males occur in discrete morphs. We show the red male polymorphism in P. picta extends continuously throughout the body and is not a Y-linked trait despite the theoretical prediction that sexually-selected characters should often be linked to the heterogametic sex chromosome. The presence/absence of red male coloration of P. picta described here makes this an ideal system for phylogenetic comparisons that could reveal the evolutionary forces maintaining mate choice and color polymorphisms in this speciose group.

Document type: 
Article
File(s): 

Ranking Mammal Species for Conservation and the Loss of Both Phylogenetic and Trait Diversity

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2015
Abstract: 

The 'edge of existence' (EDGE) prioritisation scheme is a new approach to rank species for conservation attention that aims to identify species that are both isolated on the tree of life and at imminent risk of extinction as defined by the World Conservation Union (IUCN). The self-stated benefit of the EDGE system is that it effectively captures unusual 'unique' species, and doing so will preserve the total evolutionary history of a group into the future. Given the EDGE metric was not designed to capture total evolutionary history, we tested this claim. Our analyses show that the total evolutionary history of mammals preserved is indeed much higher if EDGE species are protected than if at-risk species are chosen randomly. More of the total tree is also protected by EDGE species than if solely threat status or solely evolutionary distinctiveness were used for prioritisation. When considering how much trait diversity is captured by IUCN and EDGE prioritisation rankings, interestingly, preserving the highest-ranked EDGE species, or indeed just the most threatened species, captures more total trait diversity compared to sets of randomly-selected at-risk species. These results suggest that, as advertised, EDGE mammal species contribute evolutionary history to the evolutionary tree of mammals non-randomly, and EDGE-style rankings among endangered species can also capture important trait diversity. If this pattern holds for other groups, the EDGE prioritisation scheme has greater potential to be an efficient method to allocate scarce conservation effort.

Document type: 
Article
File(s): 

Supplementary Material: Phylogeny of all seeded plant families

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2015-10-05
Abstract: 

Climate change is driving rapid and accelerating shifts in range limits, both poleward expansions and equatorward contractions.  However, many species are falling behind the pace of change in their dispersal into newly suitable habitats and now show “climate debts”, lags between predicted and observed range expansions under changing climates. Failure to track changing climates may be due to interspecific interactions such as particular food availability for specialists, abiotic barriers such as mountain ranges, or intrinsic traits such as dispersal limitation. A trait-based analysis of climate change performance would help identify causes of climate debt.

To understand the correlates of climate debt within a large clade of organisms we use historical and modern observations of butterflies from western Canada as a case study to construct and project individual climate-based environmental niche models. By comparing projected distributions based on historical records to observed modern distributions we are able to construct estimates of climate debt and evaluate the effect of dispersal ability, diet breadth and a proxy for range size on these species' measured climate debt.

High levels of climate debt are accumulating within the butterflies of Western Canada, independently of dispersal ability, diet breadth and phylogeny. Range size emerges as the only variable that significantly reduces climate debt, suggesting that more narrowly-ranged species may be at risk of being squeezed out by both a reduction of suitable habitat in their current range and the failure to colonize newly available habitat. These findings underscore the need to investigate potential landscape-level determinants of climate debt that may be limiting range expansions in this group.

Document type: 
Dataset

Supplemental Material - 1000 randomly-chosen candidate topologies for the Canadian butterfly phylogeny

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2015-10-05
Abstract: 

Climate change is driving rapid and accelerating shifts in range limits, both poleward expansions and equatorward contractions. However, many species are falling behind the pace of change in their dispersal into newly suitable habitats and now show “climate debts”, lags between predicted and observed range expansions under changing climates. Failure to track changing climates may be due to interspecific interactions such as particular food availability for specialists, abiotic barriers such as mountain ranges, or intrinsic traits such as dispersal limitation. A trait-based analysis of climate change performance would help identify causes of climate debt.

To understand the correlates of climate debt within a large clade of organisms we use historical and modern observations of butterflies from western Canada as a case study to construct and project individual climate-based environmental niche models. By comparing projected distributions based on historical records to observed modern distributions we are able to construct estimates of climate debt and evaluate the effect of dispersal ability, diet breadth and a proxy for range size on these species' measured climate debt.

High levels of climate debt are accumulating within the butterflies of Western Canada, independently of dispersal ability, diet breadth and phylogeny. Range size emerges as the only variable that significantly reduces climate debt, suggesting that more narrowly-ranged species may be at risk of being squeezed out by both a reduction of suitable habitat in their current range and the failure to colonize newly available habitat. These findings underscore the need to investigate potential landscape-level determinants of climate debt that may be limiting range expansions in this group.

Document type: 
Dataset
Other

Valuing Species on the Cheap

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2015
Document type: 
Article
Dataset

Does the Earth's Magnetic Field Serve as a Reference for Alignment of the Honeybee Waggle Dance?

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-12-26
Abstract: 

The honeybee (Apis mellifera) waggle dance, which is performed inside the hive by forager bees, informs hive mates about a potent food source, and recruits them to its location. It consists of a repeated figure-8 pattern: two oppositely directed turns interspersed by a short straight segment, the “waggle run”. The waggle run consists of a single stride emphasized by lateral waggling motions of the abdomen. Directional information pointing to a food source relative to the sun's azimuth is encoded in the angle between the waggle run line and a reference line, which is generally thought to be established by gravity. Yet, there is tantalizing evidence that the local (ambient) geomagnetic field (LGMF) could play a role. We tested the effect of the LGMF on the recruitment success of forager bees by placing observation hives inside large Helmholtz coils, and then either reducing the LGMF to 2% or shifting its apparent declination. Neither of these treatments reduced the number of nest mates that waggle dancing forager bees recruited to a feeding station located 200 m north of the hive. These results indicate that the LGMF does not act as the reference for the alignment of waggle-dancing bees.

Document type: 
Article
File(s): 

(R)-Desmolactone Is a Sex Pheromone or Sex Attractant for the Endangered Valley Elderberry Longhorn Beetle Desmocerus californicus dimorphus and Several Congeners (Cerambycidae: Lepturinae)

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-12-18
Abstract: 

We report here that (4R,9Z)-hexadec-9-en-4-olide [(R)-desmolactone] is a sex attractant or sex pheromone for multiple species and subspecies in the cerambycid genus Desmocerus. This compound was previously identified as a female-produced sex attractant pheromone of Desmocerus californicus californicus. Headspace volatiles from female Desmocerus aureipennis aureipennis contained (R)-desmolactone, and the antennae of adult males of two species responded strongly to synthetic (R)-desmolactone in coupled gas chromatography-electroantennogram analyses. In field bioassays in California, Oregon, and British Columbia, traps baited with synthetic (R)-desmolactone captured males of several Desmocerus species and subspecies. Only male beetles were captured, indicating that this compound acts as a sex-specific attractant, rather than as a signal for aggregation. In targeted field bioassays, males of the US federally threatened subspecies Desmocerus californicus dimorphus responded to the synthetic attractant in a dose dependent manner. Our results represent the first example of a “generic” sex pheromone used by multiple species in the subfamily Lepturinae, and demonstrate that pheromone-baited traps may be a sensitive and efficient method of monitoring the threatened species Desmocerus californicus dimorphus, commonly known as the valley elderberry longhorn beetle.

Document type: 
Article
File(s): 

Measuring Evolutionary Isolation for Conservation

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2014-12-10
Abstract: 

Conservation planning needs to account for limited resources when choosing those species on which to focus attention and resources. Currently, funding is biased to small sections of the tree of life, such as raptors and carnivores. One new approach for increasing the diversity of species under consideration considers how many close relatives a species has in its evolutionary tree. At least eleven different ways to measure this characteristic on phylogenies for the purposes of setting species-specific priorities for conservation have been proposed. We find that there is much redundancy within the current set, with three pairs of metrics being essentially identical. Non-redundant metrics represent different trade-offs between the unique evolutionary history represented by a species verses its average distance to all other species. Depending on which metric is used, species priority lists can differ as much as 85% for the top 100 species. We call for some consensus on the theory behind these metrics and suggest that all future developments are compared to the current published set, and offer scripts to aid such comparisons.

Document type: 
Article
File(s):