Facultative Matrotrophy in the Livebearing Fish, Gambusia geiseri: Implications for the Evolution of Matrotrophy in the Family Poeciliidae

活鱼 Gambusia geiseri 的兼性肥大：对 Poeciliidae 科肥大进化的影响

• 批准号: 0096568
• 负责人: Edith Marsh-Matthews
• 金额: $ 30万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-15 至 2005-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0096568&HistoricalAwards=false
• 关键词: Facultative; Matrotrophy; Livebearing; Fish; Gambusia

Livebearing fishes of the Family Poeciliidae exhibit a variety of developmental strategies. In theguppy, young develop in the ovary from the energy stored in large, yolky eggs (lecithotrophy), whereas inthe least killifish, the eggs are very small, with little yolk, and most energy for development and growth istransferred from the mother to the embryo through a placenta-like structure (obligate matrotrophy). Otherspecies exhibit a mixed strategy in which energy stored in relatively large eggs is supplemented bymaternal transfer of nutrients during embryonic development (supplemental matrotrophy). The type ofstrategy exhibited by a given species has been suggested to reflect the productivity of the environmentthat it inhabits. Obligate matrotrophs are predicted to occur only in highly productive environments wherefood for the mother is abundant and predictable. In less productive or less predictable environments,lecithotrophy is the expected strategy. Species that exhibit supplemental matrotrophy may inhabitunpredictable environments but be capable of exploiting excess food if it occurs and passing extra energyon to developing offspring (facultative supplemental matrotrophy).The largespring gambusia has traditionally been considered to be strictly lecithotrophic, butrecent studies have demonstrated mother-to-embryo transfer of nutrients in this species despite theabsence of an obvious placental structure. This study proposes to use radiolabeled nutrients to quantifymatrotrophic contribution in largespring gambusia in order to address the following questions: What isthe nature of the mother-embryo transfer surface and how does it limit the amount or types of nutrientstransferred? To what extent does the largespring gambusia exhibit matrotrophy under natural conditions?How does matrotrophic contribution vary with environmental conditions within a given population andamong different populations? Understanding the occurrence of facultative matrotrophy, both acrosshabitats and temporally within habitats, may help explain the variety of developmental strategies withinthe Family Poeciliidae and the relationship of those strategies to environmental productivity. Furthermore,the strategy of facultative matrotrophy itself may reflect an adaptation to unpredictable environments thatallows species exhibiting this strategy to occupy habitats that undergo natural environmental variation.This strategy, then, may provide an important buffer against human-induced environmental changes.

Poeciliidae 科的活鱼表现出多种发育策略。在孔雀鱼中，幼鱼在卵巢中通过储存在大的蛋黄卵中的能量发育（卵黄营养），而在最小的鳉鱼中，卵非常小，蛋黄很少，并且大部分发育和生长的能量通过胎盘样结构从母体转移到胚胎（专性卵黄营养）。其他物种则表现出混合策略，其中储存在相对较大的卵中的能量通过胚胎发育过程中母体转移的营养物质进行补充（补充性营养）。有人建议，特定物种所表现出的策略类型反映了其栖息环境的生产力。据预测，专性营养生物只会出现在母亲食物丰富且可预测的高生产力环境中。在生产力较低或不可预测的环境中，卵磷脂营养是预期的策略。表现出补充性雌性营养的物种可能生活在不可预测的环境中，但如果出现多余的食物，它们能够利用多余的食物，并将额外的能量传递给发育中的后代（兼性补充性雌性营养）。传统上，大春甘布西亚被认为是严格的卵磷脂营养型，但最近的研究表明，尽管缺乏卵子营养，但该物种的营养物质仍可从母体向胚胎转移。 胎盘结构明显。本研究建议使用放射性标记的营养物质来量化大春甘布西亚的营养贡献，以解决以下问题：母胚胎转移表面的性质是什么以及它如何限制转移的营养物质的数量或类型？在自然条件下，大春甘布西亚在多大程度上表现出雌性营养？在给定种群内以及不同种群之间，雌性营养贡献如何随环境条件而变化？了解兼性营养的发生，无论是跨生境还是在生境内，可能有助于解释Poeciliidae科内的各种发育策略以及这些策略与环境生产力的关系。此外，兼性营养策略本身可能反映了对不可预测环境的适应，这使得表现出这种策略的物种能够占据经历自然环境变化的栖息地。那么，这种策略可能为抵御人类引起的环境变化提供重要的缓冲。