Egg banks in dryland wetlands provide information on the diversity and vulnerability of branchiopod communities along a longitudinal aridity gradient

2022 ◽  
Author(s):  
Elizabeth Meyer-Milne ◽  
Luc Brendonck ◽  
Tom Pinceel
Keyword(s):  
Aridity Gradient ◽  
Egg Banks

scholarly journals Different climate sensitivity for radial growth, but uniform for tree-ring stable isotopes along an aridity gradient in Polylepis tarapacana, the world’s highest elevation tree-species

2021 ◽  
Author(s):  
Milagros Rodriguez-Caton ◽  
Laia Andreu-Hayles ◽  
Mariano S Morales ◽  
Valérie Daux ◽  
Duncan A Christie ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Carbon Source ◽  
Tree Ring ◽  
Tree Growth ◽  
Carbon Sink ◽  
Growing Season ◽  
Wood Formation ◽  
Aridity Gradient ◽  
Leaf Level ◽  
Δ13c And Δ18o

Abstract Tree growth is generally considered to be temperature-limited at upper elevation treelines. Yet, climate factors controlling tree growth at semiarid treelines are poorly understood. We explored the influence of climate on stem growth and stable isotopes for Polyepis tarapacana, the world’s highest elevation tree-species found only in the South American Altiplano. We developed tree-ring width index (RWI), oxygen (δ18O) and carbon (δ13C) chronologies for the last 60 years at four P. tarapacana stands located above 4,400 meters in elevation, along a 500-km latitude-aridity gradient. Total annual precipitation decreased from 300 to 200 mm from the northern to the southern sites. We used RWI as a proxy of wood formation (carbon sink) and isotopic tree-ring signatures as proxies of leaf-level gas exchange processes (carbon source). We found distinct climatic conditions regulating carbon-sink processes along the gradient. Current-growing season temperature regulated RWI at wetter-northern sites, while prior-growing season precipitation determined RWI at arid-southern sites. This suggests that the relative importance of temperature to precipitation in regulating tree growth is driven by site-water availability. In contrast, warm and dry growing-seasons resulted in enriched tree-ring δ13C and δ18O at all study sites, suggesting that similar climate conditions control carbon-source processes. Site-level δ13C and δ18O chronologies were significantly and positively related at all sites, with the strongest relationships among the southern-drier stands. This indicates an overall regulation of intercellular carbon dioxide via stomatal conductance for the entire P. tarapacana network, with greater stomatal control when aridity increases. The manuscript also highlights a coupling and decoupling of physiological processes at leaf level versus wood formation depending on their respectively uniform and distinct sensitivity to climate. This study contributes to better understand and predict the response of high-elevation Polylepis woodlands to rapid climate changes and projected drying in the Altiplano.

Who Counts as Family? Gamete donation and the construction of family forms in medical markets

2019 ◽  
Vol 41 (6) ◽  
pp. 831-852
Author(s):  
Laura Halcomb
Keyword(s):  
Cultural Beliefs ◽  
The United States ◽  
Third Party ◽  
Gamete Donation ◽  
Egg Banks ◽  
Sperm Donors ◽  
Egg Donors ◽  
Medical Markets ◽  
Third Party Reproduction ◽  
Qualitative Analyses

This paper examines how gender beliefs are embedded in the organizational practices of the reproductive market. Third party reproduction blurs boundaries between familial and non-familial members, making gamete banks and donation agencies important sites for studying the construction of family. Cultural beliefs about gender are implicated in the discourses and practices of these organizations, which shape and constrain the experiences and options for both gamete donors and recipient families. To evaluate this process, I conducted qualitative analyses on the recruitment materials of all of sperm banks, egg banks, and egg donation agencies in the United States. My analysis demonstrates that the reproductive market still relies on heteronormative assumptions of family. However, the extent to which these organizations facilitate participation in new, non-normative family forms breaks down along gendered lines, where sperm donors have more freedom, status, and potential to create relationships with recipient families than egg donors.

scholarly journals Zooplankton resting egg banks in permanent and temporary tropical aquatic systems

2013 ◽  
Vol 25 (3) ◽  
pp. 235-245 ◽  
Author(s):  
Luciana Rabelo Araújo ◽  
Paloma Marinho Lopes ◽  
Jayme Magalhães Santangelo ◽  
Ana Cristina Petry ◽  
Reinaldo Luiz Bozelli
Keyword(s):  
Aquatic Systems ◽  
Resting Egg ◽  
Egg Banks
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