the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
AdaScape 1.0: a coupled modelling tool to investigate the links between tectonics, climate, and biodiversity
Esteban Acevedo-Trejos
Jean Braun
Katherine Kravitz
N. Alexia Raharinirina
Benoît Bovy
Abstract. The interplay between tectonics and climate is known to impact the evolution and distribution of lifeforms, leading to present-day patterns of biodiversity. Numerical models that integrate the co-evolution of life and landforms are an ideal tool to investigate the causal links between these Earth system components. Here, we present a tool that couples an ecological-evolutionary model with a landscape evolution model (LEM). The former is based on the adaptive speciation of functional traits, where these traits can mediate ecological competition for resources, and includes dispersal and mutation processes. The latter is a computationally efficient LEM (FastScape) that predicts topographic relief based on the stream power law, hillslope diffusion, and orographic precipitation equations. We integrate these two models to illustrate the coupled behaviour between tectonic uplift and eco-evolutionary processes. Particularly, we investigate how changes in tectonic uplift rate and eco-evolutionary parameters (i.e. competition, dispersal, and mutation) influence the temporal and spatial patterns of biodiversity.
Esteban Acevedo-Trejos et al.
Status: open (until 19 Jun 2023)
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RC1: 'Comment on gmd-2023-72', Anonymous Referee #1, 26 May 2023
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General
This manuscript describes a new coupled Landscape Evolution Model (LEM) and eco-evolutionary model called AdaScape. The LEM is FastScape, a well-known model that simulates river erosion and hillslope erosion an uplifting the landscape. The authors additionally incorporate orographic precipitation into the LEM component of the model. They then couple FastScape with an eco-evolutionary model in which individuals experience trait evolution in response to selection, mutation, dispersal, and competition. The authors explore elevation and precipitation as organismal traits in the models presented in the paper. The results show that trait-mediated competition has a large influence on the number of taxa. The landscape dynamics also influence the number taxa, but most significantly the rate of uplift influences the timing of lineage diversification. I think that AdaScape will be a very useful addition to the growing field of coupled Earth-Life science models. The paper is generally well-written, and the model clearly communicated. I think the manuscript will be improved with a deeper consideration and discussion of some topics that I detail below. There are some minor grammatical and wording issues throughout that I’ve noted in the section “Technical Corrections.”
Specific Comments
Taxon Definition: If I understand the taxon definition correctly, some degree of trait divergence is necessary for speciation to be recognized in the model. However, speciation can occur (and as recent work has shown, may most frequently occur) in the absence of trait divergence. For example, Anderson and Weir (2022) compared sister species pairs of birds, mammals, and amphibians and find that the majority evolve under similar selective pressures (and show little trait divergence). I wonder if the authors have considered other definitions of taxon groups that would not require trait divergence, perhaps geographic distance and/or time. You could imagine, for example, two populations becoming isolated in lowlands across a mountain range – they may undergo allopatric speciation because of a geographic barrier even though their traits may not diverge substantially. While the current taxon definition may be useful for some specific questions, it may not be useful for replicating real-world patterns where allopatric speciation seems to be common.
Mutation: The authors implement a mutation process described as “an intergenerational stochastic variation of trait values”. I think the implementation is very reasonable, but I think it may be important (especially for geoscience readers) to clarify that the mutation process here is more conceptually complicated than a mutation rate in units base pair/time. Here, the model assumes that mutation affects a specific trait optima, when, most mutations are likely deleterious. I don’t think these additional complications need to be added to the model and they are discussed in Irwin (2012), but it would be useful for readers to know if they embark on using the code as the specific understanding of what mutation means as it has implications for the values used for rate of that process.
Line 180-181: The authors claim that the model “produces well known patterns of evolutionary branching under fewer 500 generations along a continuous gradient”. This claim requires more justification. What exactly is the pattern of branching that is observed and what aspect of it matches “well known” patterns?
Line 190: The local carrying capacity is lowered to reach a similar total abundance of ~400 individuals. Is this done by trial and error or is there a way to a priori decide on these values needed to produce models with similar abundance?
Temporal scaling: The mechanism for linking the eco-evo component of the model to the LEM in time was not clear to me until the very end of the manuscript (Lines 323-331). It would be helpful to discuss how they are linked in time (e.g. one generation = one LEM time step) earlier in the manuscript, probably in section 3.2.
Effect of competition: One of the main results from the study is that taxon richness is much higher with trait-mediated competition as compared to without trait-mediated competition. In fact, this difference seems to be greater than the comparison between a static versus dynamic landscape. Does this mean that in the face of selection and competition the landscape dynamics are not very important for generating biodiversity? I think the manuscript would be improved with a deeper consideration of the implications of their results for understanding the importance of landscape dynamics.
Figure 4G: I think there are a grey line and a thin dashed line along the x-axis that can’t be seen easily. I suggest dropping the axis down slightly below 0 so the lines can be seen. I was confused about why there were only wo lines in Figure 4G when Figure 4N has three (min, mean, max).
Figure 5: It is hard to see the 2D histogram, can the lines be darkened?
Technical Corrections (grammar, wording, etc):
Line 3: “an ideal tool” --> “ideal tools” (referring to models which is plural)
Line 12: “observed” --> “observe” (present tense)
Line 25: “challenge to study” --> “challenge of studying”
Line 25: I think “recalled” is not the right word, perhaps “utilized”?
Line 30: The final sentence of the paragraph here is a bit hard to understand but is crucial for distinguishing the model here from previous efforts where eco-evo models run on static landscapes, suggest rephrasing to better emphasize the difference.
Line 31: You aren’t generating landforms themselves, suggest rephrasing as “Generating landforms in simulations…” or “Simulating landforms…” or “Understanding how landforms are generated…”
Line 51: “which is” --> “which are” (subject is plural)
Line 182: suggest deleting the word “exemplary” which would imply two really stand-out and impressive results (where I think the authors mean two typical examples of results). Same thing on line 203.
Line 210: “the simulations ultimately reach equivalent mean, maximum, and minimum values” (of what?)
Line 218: “To large differences” ….unsure what that means, typo?
Line 253: “as the rate of uplift is getting slower” --> “as the rate of uplift slows”
Line 257: “show also” --> “also show”
Line 269: “varies” --> “vary”
Citation: https://doi.org/10.5194/gmd-2023-72-RC1
Esteban Acevedo-Trejos et al.
Model code and software
AdaScape Esteban Acevedo-Trejos, Jean Braun, Katherine Kravitz, N. Alexia Raharinirina, and Benoît Bovy https://doi.org/10.5281/zenodo.7794374
Esteban Acevedo-Trejos et al.
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