Island Biogeography in the Anthropocene and Quaternary

The realization that human activities have a major influence on ecosystems from local to global scales has given rise to the concept of the Anthropocene. However, although the influence of human activities on biodiversity is clearly significant, it remains unclear to what extent the rate and magnitude of biodiversity changes differ from pre-human dynamics. Islands are ideal model systems for understanding the relative contribution of environmental and societal variables to biodiversity change because the onset of human activities on islands can generally be clearly defined. The aim of this PhD thesis is to place human-environment interactions on islands in the context of environmental fluctuations over the Quaternary. The thesis consists of two parts. First, I quantify how island area and isolation have changed over the Quaternary as a result of climate-driven sea-level fluctuations, and analyse how these dynamics have shaped modern biodiversity patterns. Secondly, I study how human activities in the past and present have shaped island ecosystems and landscapes, and compare their rate and magnitude to pre-human dynamics. Overall, the findings of my thesis indicate that modern biodiversity patterns show legacies of past human activities but are also imprinted by environmental dynamics in deep-time. Furthermore, the rate of change following human settlement on islands can largely exceed Quaternary background rates. Therefore, my findings are in line with studies that indicate that human activities have become a major driver in shaping biodiversity across scales. Nonetheless, my comparison of islands worldwide also highlights the diverse ways in which abiotic, biotic, and anthropogenic variables have interacted across individual islands. Therefore, future studies should acknowledge that global biodiversity change can manifest differently across localities. Finally, I emphasize the importance of strengthening interdisciplinary approaches in island biogeography to enhance our understanding of biodiversity changes in the Anthropocene, and how they relate to deeptime dynamics.A constatação de que as atividades humanas exercem uma grande influência sobre os ecossistemas, da escala local à global, originou o conceito do Antropoceno. No entanto, apesar da influência das atividades humanas ser claramente significativa, ainda não está claro até que ponto a taxa e magnitude de alterações na biodiversidade diferem da dinâmica pré-humana. As ilhas constituem sistemas modelo ideais para compreender a contribuição relativa de variáveis ambientais e sociais, porque o início das atividades humanas é em geral conhecido. O objetivo desta tese de doutoramento é enquadrar as interações homem-ambiente nas ilhas no contexto das flutuações ambientais no Quaternário. A tese consiste em duas partes. Primeiro, quantifico como a área da ilha e o isolamento mudaram no Quaternário devido às flutuações do nível do mar provocadas pelo clima e analiso como essas dinâmicas moldaram os padrões modernos de biodiversidade. Em segundo lugar, estudo como as atividades humanas passadas e presentes moldaram os ecossistemas e paisagens das ilhas e comparo a sua taxa e magnitude com a dinâmica pré-humana. As conclusões de minha tese indicam que os padrões modernos de biodiversidade mostram legados de atividades humanas passadas, mas também são afectados pela dinâmica ambiental em escalas temporais longinquas. Além disso, a taxa de alterações após o povoamento humano nas ilhas pode exceder largamente taxas quaternárias antecedentes. Os meus resultados concordam com estudos mostrando que as atividades humanas têm sido um fator importante na modelação da biodiversidade ao longo do tempo. Mas a minha comparação global de ilhas também destaca diversas maneiras pelas quais variáveis abióticas, bióticas e antropogénicas interagiram entre ilhas. Estudos futuros devem reconhecer que a mudança global da biodiversidade pode manifestarse de formas diferente entre localidades. Por fim, destaco a importância de aumentar abordagens interdisciplinares na biogeografia insular para melhor compreender as mudanças da biodiversidade no Antropoceno

Global raster dataset on historical coastline positions and shelf sea extents since the Last Glacial Maximum

Motivation: Historical changes in sea level caused shifting coastlines that affected the distribution and evolution of marine and terrestrial biota. At the onset of the Last Glacial Maximum (LGM) 26 ka, sea levels were >130 m lower than at present, resulting in seaward-shifted coastlines and shallow shelf seas, with emerging land bridges leading to the isolation of marine biota and the connection of land-bridge islands to the continents. At the end of the last ice age, sea levels started to rise at unprecedented rates, leading to coastal retreat, drowning of land bridges and contraction of island areas. Although a growing number of studies take historical coastline dynamics into consideration, they are mostly based on past global sea-level stands and present-day water depths and neglect the influence of global geophysical changes on historical coastline positions. Here, we present a novel geophysically corrected global historical coastline position raster for the period from 26 ka to the present. This coastline raster allows, for the first time, calculation of global and regional coastline retreat rates and land loss rates. Additionally, we produced, per time step, 53 shelf sea rasters to present shelf sea positions and to calculate the shelf sea expansion rates. These metrics are essential to assess the role of isolation and connectivity in shaping marine and insular biodiversity patterns and evolutionary signatures within species and species assemblages. Main types of variables contained: The coastline age raster contains cells with ages in thousands of years before present (bp), representing the time since the coastline was positioned in the raster cells, for the period between 26 ka and the present. A total of 53 shelf sea rasters (sea levels <140 m) are presented, showing the extent of land (1), shelf sea (0) and deep sea (NULL) per time step of 0.5 kyr from 26 ka to the present. Spatial location and grain: The coastline age raster and shelf sea rasters have a global representation. The spatial resolution is scaled to 120 arcsec (0.333° × 0.333°), implying cells of c. 3,704 m around the equator, 3,207 m around the tropics (±30°) and 1,853 m in the temperate zone (±60°). Time period and temporal resolution: The coastline age raster shows the age of coastline positions since the onset of the LGM 26 ka, with time steps of 0.5 kyr. The 53 shelf sea rasters show, for each time step of 0.5 kyr, the position of the shelf seas (seas shallower than 140 m) and the extent of land. Level of measurement: Both the coastline age raster and the 53 shelf sea rasters are provided as TIFF files with spatial reference system WGS84 (SRID 4326). The values of the coastline age raster per grid cell correspond to the most recent coastline position (in steps of 0.5 kyr). Values range from 0 (0 ka, i.e., present day) to 260 (26 ka) in bins of 5 (0.5 kyr). A value of “no data” is ascribed to pixels that have remained below sea level since 26 ka. Software format: All data processing was done using the R programming language

Global raster dataset on historical coastline positions and shelf sea extents since the Last Glacial Maximum

Abstract Motivation Historical changes in sea level caused shifting coastlines that affected the distribution and evolution of marine and terrestrial biota. At the onset of the Last Glacial Maximum (LGM) 26 ka, sea levels were >130?m lower than at present, resulting in seaward-shifted coastlines and shallow shelf seas, with emerging land bridges leading to the isolation of marine biota and the connection of land-bridge islands to the continents. At the end of the last ice age, sea levels started to rise at unprecedented rates, leading to coastal retreat, drowning of land bridges and contraction of island areas. Although a growing number of studies take historical coastline dynamics into consideration, they are mostly based on past global sea-level stands and present-day water depths and neglect the influence of global geophysical changes on historical coastline positions. Here, we present a novel geophysically corrected global historical coastline position raster for the period from 26 ka to the present. This coastline raster allows, for the first time, calculation of global and regional coastline retreat rates and land loss rates. Additionally, we produced, per time step, 53 shelf sea rasters to present shelf sea positions and to calculate the shelf sea expansion rates. These metrics are essential to assess the role of isolation and connectivity in shaping marine and insular biodiversity patterns and evolutionary signatures within species and species assemblages. Main types of variables contained The coastline age raster contains cells with ages in thousands of years before present (bp), representing the time since the coastline was positioned in the raster cells, for the period between 26 ka and the present. A total of 53 shelf sea rasters (sea level

Tiled version of GEBCO sub ice topo 2023

To ensure usability of the Global Bathymetric Model (GEBCO 2023) across all OS platforms in the TABS R-package, without dependencies of external software, a tiled version has been generated. </p

Past connections with the mainland structure patterns of insular species richness in a continental‐shelf archipelago (Aegean Sea, Greece)

Recent research in island biogeography has highlighted the important role of late Quaternary sea‐level fluctuations in shaping biogeographic patterns in insular systems but focused on oceanic systems. Through this study, we aim investigate how late Quaternary sea‐level fluctuations shaped species richness patterns in continental‐shelf island systems. Focusing on the Aegean archipelago, we first compiled maps of the area’s geography using published data, under three sea‐level stands: (a) current; (b) median sea‐level over the last nine glacial–interglacial cycles (MSL); and (c) Last Glacial Maximum (LGM). We gathered taxon–island occurrences for multiple chorotypes of angiosperms, butterflies, centipedes, and reptiles. We investigated the impact of present‐day and past geographic settings on chorological groups by analyzing island species–area relationships (ISARs) and using generalized linear mixed models (GLMMs) selection based on multiple metrics of goodness of fit. Our results confirm that the Aegean’s geography has changed dramatically since the LGM, whereas the MSL only modestly differs from the present configuration. Apart for centipedes, paleogeographic changes affected both native and endemic species diversity through altering connections between land‐bridge islands and the mainland. On land‐bridge islands, we detected over‐representation of native species and under‐representation of endemics. Unlike oceanic islands, sea‐level‐driven increase of isolation and area contraction did not strongly shape patterns of species richness. Furthermore, the LGM configurations rather than the MSL configuration shaped patterns of endemic species richness. This suggests that even short episodes of increased connectivity with continental populations are sufficient to counteract the genetic differentiation of insular populations. On the other hand, the over‐representation of native nonendemic species on land‐bridge islands reflected MSL rather than LGM mainland connections. Our study shows that in terms of processes affecting species richness patterns, continental archipelagos differ fundamentally from oceanic systems because episodic connections with the mainland have profound effects on the biota of land‐bridge islands.In the Aegean archipelago, the shorter lasting configurations of the Late Glacial Maximum promoted increased connectivity with the mainland, thereby counteracting processes promoting endemism. This result contrasts strongly with observations made on oceanic island, where longer lasting configurations largely shaped the current species diversity. This highlights that, in terms of processes affecting species richness patterns, continental archipelagos differ fundamentally from oceanic systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/1/ece37438-sup-0002-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/2/ece37438-sup-0010-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/3/ece37438-sup-0008-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/4/ece37438-sup-0003-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/5/ece37438_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/6/ece37438-sup-0004-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/7/ece37438-sup-0009-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/8/ece37438.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/9/ece37438-sup-0011-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/10/ece37438-sup-0007-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/11/ece37438-sup-0006-A3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167749/12/ece37438-sup-0005-A3.pd

Paleo Islands and Archipelago Configuration (PIAC) database

The Paleo Islands and Archipelago Configuration (PIAC) database containins sea level driven paleogeography changes over the late Quaternary of 178 islands in 27 archipelagos. The workflow developed to calculate archipelago configuration and paleo-area is provided to allow calculations for other islands, time steps, and higher spatiotemporal resolutions

Historic coastline age raster (AGE 2019)

DESCRIPTION: Global paleo drowning map indicating the most recent 500 yr time period a pixel was land. The reconstruction was done using the global bathymetric model (GEBCO 2019) and a state-of-the-art global spatiotemporal sea level curve. The global sea level curve was generated using the software SELEN4 (10.5281/zenodo.3520451) and raster DEMSRE3a (10.5281/zenodo.1637816). MAPPED CATEGORIES: from 0 to 260 in bins of 5 (e.g., 0, 5, 10, 15, 20, ..., 260; each bin corresponds to 500 yr) 0 = 0 yr BP 5 = 500 yr BP 10 = 1000 yr BP ... ... 100 = 10000 yr BP ... ... 200 = 20000 yr BP ... ... 260 = 26000 yr BP MAPPED NA VALUES: No Data = pixel has always been Below (Past) Sea Level since 26000 BP. SPATIAL RESOLUTION: The spatial resolution of the dataset is a factor 8 of the original GEBCO. TEMPORAL RESOLUTION: Temporal mapping resolution is 500 yr. DIRECTORY STRUCTURE: The dataset is provided in two formats: 1. TILED IN ASCII (AGE_tiles.zip): tiles of 10x10 degrees each representing the drowning age. File naming: structure: AGE--.asc example: AGE-10-010-020.asc description: Tile with drowning age from 0 to 10 degrees latitude, and 10 to 20 degrees longitude. 2. MOSAIC IN TIF (AGE_mosaic.tif): Global drowning map. File naming: structure: AGE.tif example: AGE.tif description: Global drowning ma

Spatial polygons for Sunda, Timor, and Caribbean regions.

DESCRIPTION: Spatial polygons for Sunda, Timor, and Caribbean regions. These are used for drawing region-scale figures (Fig. S2) CAUTION: These are hand-drawn to roughly capture the tendencies around the focal regions

Spatio-Temporal Relative Sea Level Curve (RSL)

DESCRIPTION: The spatio-temporal relative sea level curve (RSL) was developed using the software SealEveL EquatioN solver - version 4 (SELEN4; https://zenodo.org/record/3520451) (Spada et al. 2019), the global ice sheet reconstruction (ICE-5G (VM2); https://pmip2.lsce.ipsl.fr/design/ice5g/) (Peltier 2004) and DEMSRE3a (https://zenodo.org/record/1637816). MAPPED VALUES: Relative sea level stand below present in meter. SPATIAL RESOLUTION: The spatial resolution of the dataset is 0.2 degrees (WGS84). TEMPORAL RESOLUTION: Relative sea level for every 500 years from 0 BP to 26000 BP. The dataset is provided in two formats: 1. TILED IN ASCII (RSL_tiles.zip): 53 tiles of 10x10 degrees per folder each representing the relative sea level for a 500 yr time period. Directory naming: structure: //RSL..asc example: 10/010-020/RSL.005.asc description: Tile with relative sea level from 0 to 10 degrees latitude, and 10 to 20 degrees longitude, per 500 yr BP. 2. MOSAIC IN TIF (RSL_mosaic.zip): 53 global maps each presenting the relative sea level for a 500 yr time period. File naming: structure: RSL.tif example: RSL005.tif description: Relative sea level map per 500 yr BP