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Current projects:

  • Evolutionary developmental morphology of cartilaginous fishes
  • Evolutionary history of elasmobranchs (sharks, rays, and skates)
  • Elasmobranch fishes (sharks, skates, and rays) of the Adriatic Sea

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Evolutionary developmental morphology of cartilaginous fishes


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

This research area combines the traditional domain of palaeobiology with developmental morphology and developmental genetics. This project focus on the early ontogenetic development of chondrichthyan fishes, which constitute one of the two major crown groups of gnathostomes with an evolutionary history ranging back some 420 million years (probably even far more when isolated fragments are considered). The focus currently is on elasmobranch fishes (sharks, skates, rays) that become more and more model organisms for understanding the development of gnathostome traits. Here, we intend to identify phylotypic stages (= point of time when embryos of one species resemble those of others) across extant chondrichthyan clades during embryological development to provide detailed staging sequences for different clades. Timing shifts during the development of different species are well known but not yet established. These shifts in the developmental timing of organs and skeletal structures denote developmental autonomy and signify heterochronic developmental patterns. Heterochrony is a fundamental concept in macroevolutionary research. It describes time shifts of developmental events, which changed during evolution. Here, concepts and methodological approaches of morphological integration (= tendancy of different traits to vary jointly) and modularity (= modules characterized by concentration of integrated morphological traits) by employing different approaches such as Geometric Morphometrics, matrix correlations, and principal component and principal coordinate analyses but also developmental genetic approaches will be combined. This research topic thus focuses on the connection of developmental morphological trait evolution within a phylogenetic framework of cartilaginous fishes to better understand processes underlying diversification and taxonomic diversity patterns through time. The relationships between early developmental and evolutionary character transformation still also is one of the major controversies in palaeobiology since the times of E. Haeckel (1866), who proposed the recapitulation theory. Thus, we seek to better understand, how organs develop during early ontogeny and how this developmental traits relate to macroevolutionary patterns.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Dr. C. Pfaff (Co-IP)
  • Claudia Klimpfinger (PhD student)
  • Faviel López Romero (PhD student
  • Julia Türtscher (MSc student)

Collaborations:
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Evolutionary History of Elasmobranchs (Sharks, Rays, and Skates)


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

It is obvious that the taxonomy, systematics and evolutionary topics of fossil (and even extant) elasmobranchs (sharks, rays, and skates), which represent crown chondrichthyans remain incompletely known and understood despite all progress that has been accomplished in the last decades. This is mainly due to the lack of comprehensive morphological studies of fossil specimens including teeth, cranial and postcranial characters. Generally, fossil elasmobranchs are only known from their teeth, placoid scales and isolated fin spines. In some localities, however, articulated skeletal remains largely to our knowledge of past elasmobranch anatomies and that might help, for instance, to infer character changes during their evolution. The limited data sets and inaccurate faunal descriptions continue to form a serious problem in analysing past diversity and related evolutionary patterns. Some of the problems could be corrected in the studies presented here by employing different phylogenetic methods such as cladistic principles based on parsimonious and Bayesian approaches and supertree methodologies including morphological traits and genetic marker sequences, but also statistical procedures to understand adaptive traits and disparities through time. It is also possible to infer distributional and diversity patterns from the data available and to interpret this in a non-phylogenetic framework. The fundamental goal of this research topic is to gain new and deeper insights into macroevolutionary patterns and processes of elasmobranchs such as their origin, diversity fluctuations, early evolution, mechanisms underlying evolutionary processes and novelties, and timing of diversification events. The emphasis of this research lies on post-Triassic forms, because the pre-Jurassic record of elasmobranchs comprises only a single identified group of stem-line representatives according to our current knowledge. Nevertheless, sister groups to elasmobranchs, such as the hybodontiforms and other more basal positioned taxa will be included in this research topic. Most of the research is dedicated to identifying extinct elasmobranchs taxa and characters that can be used for taxonomic and systematic purposes. This information forms the basis for drawing general patterns of their early evolution, especially during the Jurassic. The Jurassic undoubtedly represents one of the most crucial periods in the evolution of elasmobranchs when most modern clades had their first appearance in the fossil record. However, stem-group representatives such as some members of Synechodontiformes but also other Palaeozoic sharks displaying characteristic histological tooth patterns that indicate closer relationships to elasmobranchs than to other groups suggest that the total-clade Elasmobranchii originated in the Palaeozoic and underwent several phases of diversification. The ultimate objective of this project thus is to reconstruct and understand the mechanisms underlying evolutionary processes, the importance of plesiomorphic characters in the evolution of elasmobranchs, to reconstruct diversity fluctuations and analyse (adaptive) radiation events.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Dr. Sebastian Stumpf (Co-IP)
  • Jaime Villafaña (PhD student)
  • Patrick L. Jambura (PhD student

Collaborations:
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Elasmobranch fishes (sharks, skates, and rays) of the Adriatic Sea


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

Elasmobranch (sharks, rays, and skates) populations are seriously endangered because of direct and indirect human impacts. As a consequence of intense exploitation, many species are listed in the Red List by the International Union for Conservation of Nature (IUCN) either as vulnerable or endangered. They are exceedingly vulnerable due to their low growth rates, late sexual maturi-ty and low fecundity. Nevertheless, no reliable studies are available for several parts of the Medi-terranean Sea and it currently is difficult to predict how reduction and/or loss of the top predators will modify marine ecosystems.The Adriatic Sea as part of the Mediterranean Sea is a semi-closed basin occupying the northernmost Mediterranean section. It extends from northwest to southeast for almost 800 km and has an averaged width of 200 km. The Strait of Otranto connects the sub-basin to the Ionian Sea and enables water exchange with the Mediterranean Sea. The northern Adriatic show a 35 m mean depth with a slight slope to the middle part which has an average depth of 140 m. The middle Adriatic is characterized by two depressions reaching 273 m maximum depth. The south-ern sub-basin has a steep continental slope and an abyssal plain. The south Adriatic Pit reaches 1330 m maximum depth. The Adriatic is a shallow sea and most area (around 73 %) is less than 200 m deep. It is a temperate warm sea and extremes of surface temperature range from 6 ºC to 29 ºC. Even the deepest layers are generally above 10 ºC. In winter central and northern parts are 8 to 10 ºC colder than the south Adriatic. The Adriatic basin has generally a cyclonic circulation with seasonal determining sub-basin gyres (AdriaMed, 2005). In the Adriatic Sea 28 sharks, 24 batoids and one chimaera are known as permanent resident or occasionally visiting.The Kvarner area is a part of the northern Adriatic Sea and divided into Rijeka Bay, the Kvarner Bay, Kvarnerić and the Velebit and Vinodol channels. The flat Rijeka Bay is about 60 m deep as well as the Vinodol Channel that decreases further north to a depth of under 40 m. There are narrow and elongated parts between the islands Krk to Rab and Rab to Pag which ex-ceed 100 m depth. The Krusija Channel is located between the islands Cres and Plavnik and shows the Northern Adriatic deepest point of 125 m. Most of the Kvarner area seafloor is covred by muddy and sandy sediments.The goals of this project are to (1) establish the taxonomic diversity of sharks, rays, and skates in the Kvarner bay, (2) construe the state of populations, (3) describe new discoveries, and (4) ascertain the implementation of possible conservation measurements.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Anna Schipany (MSc student)
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Evolution and Adaptation of Fishes to the Deep-Sea


Primary Investigator: Univ.-Prof. Dr. Jürgen Kriwet



Background & Goals:

The adaptation of fishes to deep-sea conditions is another emerging topic. Generally, it is assumed that the modern deep-sea benthic fish fauna originated in shallow waters and subsequently replaced ancient deep-sea assemblages, which became eliminated by mass extinction events. This indicates that extinction events are the main trigger for deep-sea colonization of fishes. It also is generally assumed that plesiomorphic ray-finned fish groups have more deep-sea representatives than derived ones. This study, however, is based on maximum depth occurrence data of living forms, which might be prone to error as these authors indicate. The timing and underlying processes / reasons remain ambiguous. Moreover, no definition for deep-sea fishes currently exists. Here, we intend to identify key innovations in the musculoskeletal system and to establish morphological traits for identifying deep-sea fishes. This is essential for reconstructing evolutionary traits and pathways of modern deep-sea fishes. Additionally, reliable fossil record analyses for dating such adaptive events but also diversifications in the deep will be developed and employed for providing alternative hypotheses to those currently based on molecular clocks.

Team

  • Univ.-Prof. Dr. Jürgen Kriwet (PI)
  • Dr. Cathrin Pfaff (Co-IP)

Collaborations:
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