[Herpetology • 2016] Volcanic Ash from Puyehue-Cordón Caulle Eruptions affects Running Performance and Body Condition of Phymaturus Lizards in Patagonia, Argentina

Figure 2. Photographs of the species and the study sites showing the main landscape elements and ash deposition in the southern–central steppe of Rio Negro Province, Argentina.
Abi-Saad farm (A, C) where Phymaturus sinervoi occurs and Ojo de Agua (B, D) where P. excelsus occurs.

  DOI:  10.1111/bij.12778 

Abstract

The Puyehue-Cordón Caulle eruption of 4 June 2011 dispersed about 100 million tonnes of pyroclastic materials resulting in ash accumulations of 30 cm depth on the Patagonian steppe, an area occupied by several lizard species. Herein we analysed, by experimental trials, the effects of ash and slope on running performance of two endemic and vulnerable species, Phymaturus excelsus and Phymaturus sinervoi, restricted to volcanic rock outcrops in Patagonia. We also determined the effect of ash fall on body condition by comparing the same populations before and after the volcanic eruption. Locomotion of P. excelsus, adapted to rocky and steep outcrops, was more affected in a negative way by ash. In contrast, P. sinervoi, which lives in mixed habitats with flat rocks and sandy substrates, ran more slowly on the inclined surface but was unaffected by ash, suggesting the two species are well adapted to the habitats they occupy. In spite of impacts of ash deposition on locomotion and potentially the feeding, reproduction and dispersal activity of P. excelsus, lizards captured 18 months after ash deposition showed improved body condition. Our study site for P. sinervoi received less ash deposition and hence body condition was similar before and after ash fall. We hypothesize that negative effects of ash on lizards were counteracted by competitive release; ash deposition caused an acute and significant increase in mortality of herbivorous competitors such as hares and sheep that feed upon the same flowers and fruits included in the Phymaturus diet.

Keywords: body condition; disturbance; maximum running speed; Phymaturus excelsus; Phymaturus sinervoi

Nora R. Ibargüengoytía, Facundo Cabezas-Cartes, Jorgelina M. Boretto, Carla Piantoni, Erika L. Kubisch, Mariela S. Fernández, Rafael A. Lara-Resendiz, Fausto R. Méndez-de la Cruz, Alejandro Scolaro and Barry Sinervo. 2016. Volcanic Ash from Puyehue-Cordón Caulle Eruptions affects Running Performance and Body Condition of Phymaturus Lizards in Patagonia, Argentina. Biological Journal of the Linnean Society. DOI:  10.1111/bij.12778 

[Herpetology • 2015] Hybridization masks Speciation in the Evolutionary History of the Galápagos Marine Iguana Amblyrhynchus cristatus

Figure 1. Temporal framework of iguana evolution on the Galápagos Islands.
(a) Partial timetree based on four nuclear genes (3000 bp) time-calibrated using multiple time constraints applied to a total dataset of 78 squamates (full tree in electronic supplementary material, figure S1). Numbers at nodes indicate support from partitioned BI analyses (posterior probability values; PP) and maximum-parsimony (MP) bootstrapping (bootstrapping values; BS); asterisks indicate maximum support. Bars are 95% credibility intervals of time estimates.
 (b) Maximum credibility tree from a partitioned BI analysis of 5557 bp of mtDNA. Black asterisks indicate concordant maximum support from a partitioned BI analysis, timetree analysis and MP bootstrap analysis. Small grey asterisks indicate high support (PP > 0.94; BS > 70%) from at least two of these analyses. Time estimates and 95% credibility intervals from a timetree analysis are given at selected nodes.

DOI: 10.1098/rspb.2015.0425

ABSTRACT 

The effects of the direct interaction between hybridization and speciation-two major contrasting evolutionary processes-are poorly understood. We present here the evolutionary history of the Galápagos marine iguana (Amblyrhynchus cristatus) and reveal a case of incipient within-island speciation, which is paralleled by between-island hybridization. In-depth genome-wide analyses suggest that Amblyrhynchus diverged from its sister group, the Galápagos land iguanas, around 4.5 million years ago (Ma), but divergence among extant populations is exceedingly young (less than 50 000 years). Despite Amblyrhynchus appearing as a single long-branch species phylogenetically, we find strong population structure between islands, and one case of incipient speciation of sister lineages within the same island-ostensibly initiated by volcanic events. Hybridization between both lineages is exceedingly rare, yet frequent hybridization with migrants from nearby islands is evident. The contemporary snapshot provided by highly variable markers indicates that speciation events may have occurred throughout the evolutionary history of marine iguanas, though these events are not visible in the deeper phylogenetic trees. We hypothesize that the observed interplay of speciation and hybridization might be a mechanism by which local adaptations, generated by incipient speciation, can be absorbed into a common gene pool, thereby enhancing the evolutionary potential of the species as a whole.

KEYWORDS: restriction site-associated DNA (RAD) sequencing, single-nucleotide polymorphisms, El Niño, volcanism, introgressive hybridization, morphometrics

Figure 1. Temporal framework of iguana evolution on the Galápagos Islands. (a) Partial timetree based on four nuclear genes (3000 bp) time-calibrated using multiple time constraints applied to a total dataset of 78 squamates (full tree in electronic supplementary material, figure S1). Numbers at nodes indicate support from partitioned BI analyses (posterior probability values; PP) and maximum-parsimony (MP) bootstrapping (bootstrapping values; BS); asterisks indicate maximum support. Bars are 95% credibility intervals of time estimates. (b) Maximum credibility tree from a partitioned BI analysis of 5557 bp of mtDNA. Black asterisks indicate concordant maximum support from a partitioned BI analysis, timetree analysis and MP bootstrap analysis. Small grey asterisks indicate high support (PP > 0.94; BS > 70%) from at least two of these analyses. Time estimates and 95% credibility intervals from a timetree analysis are given at selected nodes. (c) Timetree based on a complete matrix of 1 793 845 nucDNA sequences obtained by RADSeq of three Galápagos marine iguanas (selected to represent the deepest splits within the species) and one land iguana (Conolophus pallidus), showing the extremely shallow divergences within Amblyrhynchus.

 DOI: 10.1098/rspb.2015.0425

An adult male marine iguana (Amblyrhynchus cristatus) of the Loberia type, at the ‘La Loberia’ colony on San Cristóbal Island.

photo: Amy MacLeod 

No ugly at all - marine iguanas are fascinating inhabitants of the Galápagos islands and the only sea going lizard world-wide

photo: Alejandro Ibáñez Ricomá

Coming a long way - a red migrant marine iguana from Española on San Cristóbal island

photo: Amy MacLeod

Amy MacLeod, Ariel Rodríguez, Miguel Vences, Pablo Orozco-terWengel, Carolina García, Fritz Trillmich, Gabriele Gentile, Adalgisa Caccone, Galo Quezada and Sebastian Steinfartz. 2015. Hybridization masks Speciation in the Evolutionary History of the Galápagos Marine Iguana. Proceedings of the Royal Society B: Biological Sciences. 282(1809). DOI: 10.1098/rspb.2015.0425

ResearchGate.net/publication/277780935_Hybridization_masks_speciation_in_the_evolutionary_history_of_the_Galpagos_marine_iguana

..........

Hybridization (the merging of species) and speciation (the diversification of populations into species) are classically seen as opposing evolutionary processes. However, this study on Galapagos marine iguanas, the only seagoing lizard worldwide, offers novel insights into how these processes can act in concert. On San Cristóbal Island it was found that two resident populations of marine iguanas behave as distinct species from one another; they do not interbreed and they have morphological differences. This is the smallest island in which a speciation process in a highly mobile animal has been found. However these two populations also seem to breed freely with migrant iguanas from other Islands.

The research team believe that the combination of speciation between populations generates new adaptations and then hybridization between these populations absorbs those adaptations into a common genepool. This may enhance the evolutionary success of marine iguanas and help to explain their persistence on the archipelago (they are one of the oldest vertebrates of the Islands). However, the divergence between marine and land iguanas is far more recent than was previously thought, and it seems that they diverged around 4.5 million years ago which is about the same age as the oldest of the present Islands.

The Evolutionary History of the Galapagos Marine Iguana - Galapagos Conservation Trust Blog [@galapagossip] https://shar.es/12Yoew 

Darwin’s ugly duckling surprises evolutionary biologists http://www.idw-online.de/-CaVMAA

[Geology / News • 2013] Nishima-Shima Volcano: Submarine Volcanic Eruption Gives Birth to New Island Off Japan

Nishima-Shima Volcano

: Submarine Volcanic Eruption Gives Birth to New Island Off Japan

A new island was born today [20 Nov 2013] in the Pacific Ocean in Japan's Izu (or Volcano) island chain. It is produced by a new submarine eruption which is currently taking place about 500 m southeast of Nishino-Shima island. 

The eruption was first spotted by Japanese navy this morning at 10:20 (local time) who documented surtseyan activity at the eruption site (explosive interaction of sea-water and lava, generating violent jets of steam and ash). It appears that the eruption has already built an island of about 200 m diameter in size, which suggests that the vent was already located in very shallow waters. 

A small steam and ash plume rising to about 600 m. was reported by VAAC Tokyo. The last known eruption of the volcano occurred in 1973 .

Underwater Volcanic Eruption Gives Birth To New Island Off Japan
http://www.buzzfeed.com/mbvd/underwater-volcanic-eruption-gives-birth-to-new-island-off-j via @michellebvd

Nishima-Shima volcano (Japan): submarine volcanic eruption gives birth to new island

http://www.volcanodiscovery.com/nishino-shima/news/38948/Nishima-Shima-volcano-Japan-submarine-volcanic-eruption-gives-birth-to-new-island.html

[Geology • 2013] Seismic Detection of an Active Subglacial Magmatic Complex in Marie Byrd Land, Antarctica | Volcano Discovered Smoldering Under a Kilometer of Ice in West Antarctica

Mount Sidley, the highest volcano in Antarctica, may have a lot of company lurking out of sight. Scientists are using seismographs to hunt for hidden volcanoes in Antarctica.

photo: Doug Wiens

Abstract

Numerous volcanoes exist in Marie Byrd Land, a highland region of West Antarctica. High heat flow through the crust in this region may influence the stability of the West Antarctic Ice Sheet. Volcanic activity progressed from north to south in the Executive Committee mountain range between the Miocene and Holocene epochs, but there has been no evidence for recent magmatic activity. Here we use a recently deployed seismic network to show that in 2010 and 2011, two swarms of seismic activity occurred at 25–40 km depth beneath subglacial topographic and magnetic highs, located 55 km south of the youngest subaerial volcano in the Executive Committee Range. We interpret the swarm events as deep long-period earthquakes based on their unusual frequency content. Such earthquakes occur beneath active volcanoes, are caused by deep magmatic activity and, in some cases, precede eruptions. We also use radar profiles to identify a prominent ash layer in the ice overlying the seismic swarm. Located at 1,400 m depth, the ash layer is about 8,000 years old and was probably sourced from the nearby Mount Waesche volcano. Together, these observations provide strong evidence for ongoing magmatic activity and demonstrate that volcanism continues to migrate southwards along the Executive Committee Range. Eruptions at this site are unlikely to penetrate the 1.2 to 2-km-thick overlying ice, but would generate large volumes of melt water that could significantly affect ice stream flow.

Amanda C. Lough, Douglas A. Wiens, C. Grace Barcheck, Sridhar Anandakrishnan, Richard C. Aster, Donald D. Blankenship, Audrey D. Huerta, Andrew Nyblade, Duncan A. Young, Terry J. Wilson. 2013. Seismic Detection of an Active Subglacial Magmatic Complex in Marie Byrd Land, Antarctica. Nature Geoscience. 2013; DOI: dx.doi.org/10.1038/ngeo1992

Volcano Discovered Smoldering Under a Kilometer of Ice in West Antarctica

: Heat May Increase Rate of Ice Loss

 — It wasn't what they were looking for but that only made the discovery all the more exciting.

In January 2010 a team of scientists had set up two crossing lines of seismographs across Marie Byrd Land in West Antarctica. It was the first time the scientists had deployed many instruments in the interior of the continent that could operate year-round even in the coldest parts of Antarctica.

What's Under Antarctica? Quake Waves Give First Look

http://www.livescience.com/19546-antarctica-seismic-image-geology.html

http://www.sciencedaily.com/releases/2013/11/131117155609.htm

http://phys.org/news/2013-11-volcano-smoldering-kilometer-ice-west.html