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Portfolio Conservation of Metapopulations Under Climate Change

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2015-03-01
Abstract: 

Climate change is likely to lead to increasing population variability and extinction risk. Theoretically, greater population diversity should buffer against rising climate variability, and this theory is often invoked as a reason for greater conservation. However, this has rarely been quantified. Here we show how a portfolio approach to managing population diversity can inform metapopulation conservation priorities in a changing world. We develop a salmon metapopulation model in which productivity is driven by spatially distributed thermal tolerance and patterns of short‐ and long‐term climate change. We then implement spatial conservation scenarios that control population carrying capacities and evaluate the metapopulation portfolios as a financial manager might: along axes of conservation risk and return. We show that preserving a diversity of thermal tolerances minimizes risk, given environmental stochasticity, and ensures persistence, given long‐term environmental change. When the thermal tolerances of populations are unknown, doubling the number of populations conserved may nearly halve expected metapopulation variability. However, this reduction in variability can come at the expense of long‐term persistence if climate change increasingly restricts available habitat, forcing ecological managers to balance society's desire for short‐term stability and long‐term viability. Our findings suggest the importance of conserving the processes that promote thermal‐tolerance diversity, such as genetic diversity, habitat heterogeneity, and natural disturbance regimes, and demonstrate that diverse natural portfolios may be critical for metapopulation conservation in the face of increasing climate variability and change.

Document type: 
Article
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Effects of High-Fat Diets on Fetal Growth in Rodents: A Systematic Review

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-04-16
Abstract: 

Background: Maternal nutrition during pregnancy has life-long consequences for offspring. However, the effects of maternal overnutrition and/ or obesity on fetal growth remain poorly understood, e.g., it is not clear why birthweight is increased in some obese pregnancies but not in others. Maternal obesity is frequently studied using rodents on highfat diets, but effects on fetal growth are inconsistent. The purpose of this review is to identify factors that contribute to reduced or increased fetal growth in rodent models of maternal overnutrition.

Methods: We searched Web of Science and screened 2173 abstracts and 328 full texts for studies that fed mice or rats diets providing ~ 45% or ~ 60% calories from fat for 3 weeks or more prior to pregnancy. We identified 36 papers matching the search criteria that reported birthweight or fetal weight.

Results: Studies that fed 45% fat diets to mice or 60% fat diets to rats generally did not show effects on fetal growth. Feeding a 45% fat diet to rats generally reduced birth and fetal weight. Feeding mice a 60% fat diet for 4–9 weeks prior to pregnancy tended to increase in fetal growth, whereas feeding this diet for a longer period tended to reduce fetal growth.

Conclusions: The high-fat diets used most often with rodents do not closely match Western diets and frequently reduce fetal growth, which is not a typical feature of obese human pregnancies. Adoption of standard protocols that more accurately mimic effects on fetal growth observed in obese human pregnancies will improve translational impact in this field.

Document type: 
Article
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Rhodnius Prolixus: Identification of Missing Components of the IMD Immune Signaling Pathway and Functional Characterization of its Role in Eliminating Bacteria

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-04-03
Abstract: 

The innate immune system in insects is regulated by specific signalling pathways. Most immune related pathways were identified and characterized in holometabolous insects such as Drosophila melanogaster, and it was assumed they would be highly conserved in all insects. The hemimetabolous insect, Rhodnius prolixus, has served as a model to study basic insect physiology, but also is a major vector of the human parasite, Trypanosoma cruzi, that causes 10,000 deaths annually. The publication of the R. prolixus genome revealed that one of the main immune pathways, the Immune-deficiency pathway (IMD), was incomplete and probably non-functional, an observation shared with other hemimetabolous insects including the pea aphid (Acyrthosiphon pisum) and the bedbug (Cimex lectularius). It was proposed that the IMD pathway is inactive in R. prolixus as an adaptation to prevent eliminating beneficial symbiont gut bacteria. We used bioinformatic analyses based on reciprocal BLAST and HMM-profile searches to find orthologs for most of the “missing” elements of the IMD pathway and provide data that these are regulated in response to infection with Gram-negative bacteria. We used RNAi strategies to demonstrate the role of the IMD pathway in regulating the expression of specific antimicrobial peptides (AMPs) in the fat body of R. prolixus. The data indicate that the IMD pathway is present and active in R. prolixus, which opens up new avenues of research on R. prolixus-T. cruzi interactions.

Document type: 
Article
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Salmon Increase Forest Bird Abundance and Diversity

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-02-06
Abstract: 

Resource subsidies across ecosystems can have strong and unforeseen ecological impacts. Marine-derived nutrients from Pacific salmon (Onchorhycus spp.) can be transferred to streams and riparian forests through diverse food web pathways, fertilizing forests and increasing invertebrate abundance, which may in turn affect breeding birds. We quantified the influence of salmon on the abundance and composition of songbird communities across a wide range of salmon-spawning biomass on 14 streams along a remote coastal region of British Columbia, Canada. Point-count data spanning two years were combined with salmon biomass and 13 environmental covariates in riparian forests to test for correlates with bird abundance, foraging guilds, individual species, and avian diversity. We show that bird abundance and diversity increase with salmon biomass and that watershed size and forest composition are less important predictors. This work provides new evidence for the importance of salmon to terrestrial ecosystems and information that can inform ecosystem-based management.

Document type: 
Article
File(s): 

List of Imperiled Birds, Ranked By ED and Scored for Ex Situ Suitability

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2019-01-24
Abstract: 

Dataset (as excel file) with all imperiled bird species along with data that may help to guide prioritization for ex situ conservation programs. SS3a lists 506 imperiled species not currently held in ZIMS (Zoological Information Management System) global zoo networks, ranked by Evolutionary Distinctness (ED) score.  Each species is also scored for family membership, how many confamilials are in a ZIMS facility (as a measure of husbandry expertise), their biogeographical realm, and notes on whether there is evidence of non-ZIMS or non-zoo ex situ programs or holdings. Data on non-ZIMS holdings was gathered from the International Union for Conservation of Nature (2016) and personal communication from M. Lamont, S. Bruslund-Jensen and J. Lindholm III. Data from personal correspondence is accurate to the best of our current knowledge but is not exhaustive of all private or non-zoo holdings. SS3b lists 111 imperiled species found in ZIMS institutions, ranked by ED score. In addition to the criteria in SS3a, we list also list the number of female breeding individuals and total breeding individuals for captive populations (data collected from ZIMS (2017)).

Document type: 
Dataset
File(s): 

Placental Villous Hypermaturation is Associated with Improved Neonatal Outcomes

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-01-14
Abstract: 

Introduction: Accelerated placental maturation is considered a sign of maternal vascular malperfusion, and is often interpreted as an adaptive, compensatory response by the placenta. We tested this interpretation by comparing outcomes in pregnancies with and without accelerated maturation.

Methods: Using data from the National Collaborative Perinatal Project, we categorized preterm placentas (24 - 34 weeks, inclusive; 2525 births) by whether they showed placental villous hypermaturation (PVH), i.e., had the appearance of a placenta of 37 weeks or over upon microscopic examination. We assessed whether PVH was associated with maternal race, maternal BMI, fetal sex, type of preterm birth, preeclampsia, signs of infection or inflammation or placental abruption. We also assessed whether placentas showing PVH were associated with improved outcomes in terms of survival, Apgar score, or oxygen use.

Results: PVH was more common in preeclamptic pregnancies and less common in pregnancies complicated by placental abruption or showing signs of placental infection or inflammation. Adjusting for potentially confounding factors, PVH was associated with reduced odds of fetal death, death between birth and 120 days of age, low Apgar scores and oxygen use. PVH was also associated with higher birthweights for gestational age. When correcting for the effect of birthweight, the association between PVH and reduced fetal and neonatal death remained significant.

Discussion: Accelerated placental maturation, as manifested by PVH, is associated with improved outcomes. Our work therefore supports the hypothesis that accelerated maturation is a compensatory response by the placenta to improve its transport capacity in specific pregnancy complications.

Document type: 
Article

Body size variation in the sexually dimorphic scaphopod Rhabdus rectius (Carpenter, 1864) (Dentaliida: Rhabdidae)

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-11-25
Abstract: 

Male-biased sexual size dimorphism typically evolves via sexual selection for larger males that are favoured by choosy females or are more successful in mate competition with other males. Among marine invertebrates that broadcast their gametes into the ocean for fertilisation, this form of sexual size dimorphism is rare because such species lack direct interactions among males or between the sexes. However, the broadcast-spawning tusk shell Rhabdus rectius was recently reported to show strong male-biased sexual size dimorphism. That pattern might imply interesting and undiscovered sexual selection in this species. We found instead that the distribution of body size variation (weight, shell length) was similar between males and females of R. rectius, and mean sizes were not different between the sexes. However, we noted a male-biased sex ratio (~1:1.3) in our large sample of individuals. Many live scaphopods (and several dead shells) showed partial or complete boreholes drilled by predatory gastropods. Boreholes were observed on males and females in similar proportions. We collected scaphopods along with multiple individuals of one likely scaphopod predator, the small moon snail Euspira pallida, and in the lab we observed successful attacks by moon snails on tusk shells.

Document type: 
Article

Pappa2 Deletion Has Sex- and Age-Specific Effects on Bone in Mice

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-10-31
Abstract: 

Objective

In humans, loss-of-function mutations in the gene encoding pregnancy-associated pregnancy protein-A2 cause short stature and slightly reduced bone density. The goal of this study was to determine the effects of Pappa2 deletion on bone in mice.

Design

Pappa2 deletion mice and littermate controls were culled at 10, 19 or 30 weeks of age and femurs were analysed by micro-computed tomography. Serum markers of bone turnover and insulin-like growth factor binding protein 5 (IGFBP-5), a proteolytic target of PAPP-A2, were measured by ELISA.

Results

At 10 and 19 weeks of age, Pappa2 deletion mice had slightly reduced trabecular parameters, but by 19 weeks of age, female deletion mice had increased cortical tissue mineral density, and this trait was increased by a small amount in deletion mice of both sexes at 30 weeks. Cortical area fraction was increased in Pappa2 deletion mice at all ages. Deletion of Pappa2 increased circulating IGFBP-5 levels and reduced markers of bone turnover (PINP and TRACP 5b).

Conclusions

PAPP-A2 contributes to the regulation of bone structure and mass in mice, likely through control of IGFBP-5 levels. The net effect of changes in bone formation and resorption depend on sex and age, and differ between trabecular and cortical bone

Document type: 
Article
File(s): 

Palladin Compensates for the Arp2/3 Complex and Supports Actin Structures during Listeria Infections

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-04-10
Abstract: 

Palladin is an important component of motile actin-rich structures and nucleates branched actin filament arrays in vitro. Here we examine the role of palladin during Listeria monocytogenes infections in order to tease out novel functions of palladin. We show that palladin is co-opted by L. monocytogenes during its cellular entry and intracellular motility. Depletion of palladin resulted in shorter and misshapen comet tails, and when actin- or VASP-binding mutants of palladin were overexpressed in cells, comet tails disintegrated or became thinner. Comet tail thinning resulted in parallel actin bundles within the structures. To determine whether palladin could compensate for the Arp2/3 complex, we overexpressed palladin in cells treated with the Arp2/3 inhibitor CK-666. In treated cells, bacterial motility could be initiated and maintained when levels of palladin were increased. To confirm these findings, we utilized a cell line depleted of multiple Arp2/3 complex subunits. Within these cells, L. monocytogenes failed to generate comet tails. When palladin was overexpressed in this Arp2/3 functionally null cell line, the ability of L. monocytogenes to generate comet tails was restored. Using purified protein components, we demonstrate that L. monocytogenes actin clouds and comet tails can be generated (in a cell-free system) by palladin in the absence of the Arp2/3 complex. Collectively, our results demonstrate that palladin can functionally replace the Arp2/3 complex during bacterial actin-based motility.

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The Roles of Extrinsic and Intrinsic Factors in the Freshwater Life-History Dynamics of a Migratory Salmonid

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-09-26
Abstract: 

Key life-cycle transitions, such as metamorphosis or migration, can be altered by a variety of external factors, such as climate variation, strong species interactions, and management intervention, or modulated by density dependence. Given that these life-history transitions can influence population dynamics, understanding the simultaneous effects of intrinsic and extrinsic controls on life-history expression is particularly relevant for species of management or conservation importance. Here, we examined how life histories of steelhead (Oncorhynchus mykiss) are affected by weather, pink salmon abundance (Oncorhynchus gorbuscha), experimental nutrient addition, and density-dependent processes. We tested for impacts on the size of steelhead smolts (juveniles migrating to the sea), as well as their age and abundance across four decades in the Keogh River, British Columbia, Canada. Larger steelhead smolts were associated with warmer years and artificial nutrient addition. In addition, higher pink salmon abundance and artificial nutrient addition correlated with juvenile steelhead migrating at younger ages. While density dependence appeared to be the primary factor regulating the abundance of steelhead smolts, nutrient addition and temperature were positively and negatively associated with smolt production, respectively, prior to 1991, and pink salmon spawning abundance was positively associated with smolt production after 1990. Thus, this study provides evidence that the temporal dynamics of one species of salmon is linked to the juvenile life history of co-occurring steelhead. A complex interplay of species interactions, nutrient subsidies, density dependence, and climatic variation can control the life-history expression of species with complex life cycles.

Document type: 
Article
File(s):