Establishment of a novel approach to trace Lake Tanganyika's gastropod faunal evolution

ICDP取芯开启了湖泊历史探索的新时代，也增加了对生物进化的关注。坦噶尼喀湖（LT）是非洲最古老和最深的湖泊，是众所周知的淡水生物多样性的全球热点。LT面临着一系列显着的变化，在生态条件，包括湖泊水位波动在不同程度上，分离和重新加入子流域，打开和关闭的盆地，以及不同的连接到主要河流系统。LT的海栖（海洋状）腹足类是任何淡水腹足类辐射的形态空间和大小占领的贝壳方面最突出的例子。值得注意的是，超级群体的起源一直在激烈的争论，但至今仍不清楚。一个令人兴奋的新方法，物种划界是蛋白质组指纹，它使用特定的质量配置文件的识别能力的肽和小蛋白质产生的基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）。另一种新的方法-壳古蛋白质组学-具有重要的潜力，一个新的代理系统重建古动物的湖泊。它将蛋白质组指纹图谱方法扩展到非生命物质，这里是嵌入软体动物外壳晶体结构中的蛋白质（所谓的晶体内蛋白质）。通过开发一个基于特定区域或生态系统中所有腹足类（和双壳类）物种的最近和化石外壳的蛋白质库，即使是经过改造和大量破坏的化石材料也可以重建古群落。这些条件往往会在湖泊沉积物，特别是在那些古老的湖泊，如坦噶尼喀湖。本提案的主要目标是了解如何非凡的生物多样性和地方性LT发展一种新的综合分析方法，采用蛋白质指纹，壳palaeoproteomics，DNA条形码和生物多样性建模，以跟踪物种多样性和（Meta）社区的演变。根据与总体科学深钻目标相关的一般问题-通过深时确定地方性生物多样性的驱动因素-本研究将针对以下具体目标：（1）建立蛋白质指纹图谱和贝壳古蛋白质组学方法;（2）鉴定和表征现代和化石腹足类组合，以空间追踪群落梯度和周转，由于许多湖泊沉积物中缺乏保存完好的化石，因此利用来自贝壳残体的晶内蛋白质组数据和来自现代分类群的库来模拟过去的重大进化事件的方法将引起地质学家和古生物学家的极大兴趣。

ICDP corings have opened a new era of exploration of lake histories and have also increased their focus on biological evolution. Lake Tanganyika (LT) is Africa’s oldest and deepest lake and well known to be a global hotspot of freshwater biodiversity. LT has faced a series of marked shifts in the ecological conditions including lake-level fluctuations at different magnitudes, separation and re-joining of sub-basins, opening and closing of the basin, and varying connections to major rivers systems. The thalassoid (marine-like) gastropods of LT represent the most outstanding example of any freshwater gastropod radiation in terms of morphospace and size occupation of the shells. Remarkable, the origin of the superflock has been intensively debated but remains unclear to date.An exciting new approach for species delimitation is proteomic fingerprinting, which uses the discriminative power of specific mass profiles of peptides and small proteins generated with Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS). Another novel approach – shell palaeoproteomics – holds significant potential for a new proxy system for reconstructing palaeofaunas of a lake. It extents the proteomic fingerprinting approach to non-living material, here proteins embedded in crystalline structure of mollusc shells (so-called intracrystalline proteins). By developing a protein library based on both recent and fossil shells of all gastropod (and bivalve) species of a particular region or ecosystem, palaeocommunities could be reconstructed even with reworked and largely destroyed fossil material. These conditions are often met in lake sediments and particular in those of ancient lakes such as Lake Tanganyika.The main goal of this proposal is to understand how the extraordinary biodiversity and endemicity in LT evolved by developing a new integrated analytical approach employing proteomic fingerprinting, shell palaeoproteomics, DNA barcoding and biodiversity modelling to trace species diversification and (meta-)community evolution. Based on general questions that are relevant for the overall scientific deep-drilling goal - Identifying drivers of endemic biodiversity through deep time - the following specific objectives will be targeted during this study: (1) Establishment of the proteomic fingerprinting and shell palaeoproteomics approach, (2) Identification and characterization of recent and fossil gastropod assemblages to spatially trace community gradients and turnover, and (3) Testing Pleistocene faunal affinities and limnological connections of LT to connected rivers and lakes Kivu and Rukwa.Due to the lack of well-preserved fossils in many lake sediments, the approach of using intracrystalline proteomic data from shell remnants and a library from recent taxa to model major evolutionary events in the past will be of great interest for geologists and palaeontologists.